(My) CSSLP Notes – Secure Software Requirements

Note: This notes were strongly inspired by the following books: CSSLP Certification All in one and Official (ISC)2 Guide to the CSSLP CBK, Second Edition

 Policy Decomposition

CSSLP-logoThe policy decomposition is the process of breaking down high level policy requirements into security objectives and eventually protection needs and secure software requirements.

Policies involving protecting data could be decomposed in confidentiality requirements.

Policies involving protecting data from unauthorized alteration can be decomposed in integrity requirement.

Policies associated with determining access can be decomposed into availability requirements.

policy decomposition

Data Classification and Categorization

Data classification is a risk management tool, with the objective to reduce the costs associated with protecting data.

Types of data :

  • structured – the most common form of structured data is that stored in the DB; other forms of structured data, XML, JSON test files, log files.
  • unstructured – the rest of data that is not structured; data that is not easily parsed and parsed.

Data states :

  • data at rest.
  • data in transit – data being transmitted from one location to another.
  • date being created.
  • data being changed or deleted.

Data labeling

Data classification/labelling is the conscious effort to assign labels (a level of sensitivity) to information (data) assets, based on potential impact to confidentiality, integrity and availability (CIA).

The main objective of data classification is to lower the cost of data protection
and maximize the return on investment when data is protected.

Data ownership:

  • Data Owner – (also called information owner or business owner) is a management employee responsible for ensuring that specific data is protected. Data owners determine data sensitivity labels and the frequency of data backup. The Data Owner is responsible for ensuring that data is protected. A user who “owns” data has read/write access to objects.
  • Data Custodian – provides hands-on protection of assets such as data. They perform data backups and restoration, patch systems, configure antivirus software, etc. The Custodians follow detailed orders; they do not make critical decisions on how data is protected.


Role and user definitions

  • objects – items that a user (subject) interacts with in the operation of a system.
  • subjects – an active entity on a data system. Most examples of subjects involve people accessing data files. However, running computer programs are subjects as well. A Dynamic Link Library file or a Perl script that updates database files with new information is also a subject.
  • actions – permitted events that a subject can perform on an associated object.
The subjects represent who, the objects represents what and actions represent the how of the subject-object-activity relationship. A subject-object matrix is used to identify allowable actions between subjects and objects based on use cases.
Once use cases are enumerated with subjects (roles) and the objects (components) are defined, a subject-object matrix can be developed. A subject-object matrix is a two-dimensional representation of roles and components.

Functional requirements

Functional requirements describe how the software is expected to function. They begin as business requirements and are translated into functional requirements.

Uses cases are a technique for determining functional requirements in developer-friendly terms. Use case modeling is meant to model only the most significant system behavior or the most complex ones and not all of it and so should not be considered as a substitute for requirements specification documentation.
 From use cases, misuse cases can be developed. Misuse cases, also known as abuse cases help identify security requirements by modeling negative scenarios.
Time of Check/Time of Use (TOCTOU) attacks are also called race conditions: an attacker attempts to alter a condition after it has been checked by the operating system, but before it is used. The term race condition comes from the idea of two events or signals that are racing to influence an activity.
Some of the common templates that can be used for use and misuse case
modeling are templates by Kulak and Guiney. On the tooling side you can take a look to Secure Quality Requirements Engineering (SQuaRE) methodology.

Requirements Traceability Matrix (RTM)

The RTM is a grid that assists the development team in tracking and managing requirements and implementation details.

A generic RTM is a table of information that lists the business requirements in the left most column, the functional requirements that address the business requirements are in the next column. Next to the functional requirements are the testing requirements. From a software assurance perspective, a generic RTM can be modified to include security requirements as well. This is a template example of RTM diagram: Requirements Traceability Matrix Template

(My) CSSLP Notes – Secure Software Concepts

Note: This notes were strongly inspired by the following book: CSSLP Certification All in one.

General Security Concepts


The security of IT systems can be defined using the following attributes:

  • confidentiality – how the system prevents the disclosure of information.
  • integrity – how the system protects data from the unauthorized access.
  • availability – access to the system by authorized personnel.
  • authentication – process of determining the identity of a user. Three methods can be used to authenticate a user:
    • something you know (ex: password, pin code)
    • something you have (ex: token, card)
    • something you are (ex: biometrics mechanisms)
  • authorization – process of applying access control rules to a user process to determine if a particular user process can access an object.
  • accounting (auditing) – records historical events on a system.
  • non-repudiation – preventing a subject from denying a previous action with an object in a system.

System principles

  • session management – design and implementation of controls to ensure that the communications channels are secured from unauthorized access and disruption of communications.
  • exception management – the process of handling any errors that could appear during the system execution.
  • configuration management – identification and management of the configuration items (initialization parameters, connection strings, paths, keys).

Secure design principles

  • good enough security – there is a trade off between security and other aspects associated with a system. The level of required security must be determined at design time.
  • least privilege – a subject should have only the necessary rights and privileges to perform a specific task.
  • separation of duties – for any given task, more than one individual needs to be involved.
  • defense in depth (layered security) – apply multiple dissimilar security defenses.
  • fail-safe – when a system experience a failure, it should fail to a safe state; all the attributes associated with the system security (confidentiality, integrity, availability) should be appropriately maintained.
  • economy of mechanism – keep the design of the system simple and less complex; reduce the number of dependencies and/or services that the system needs in order to operate.
  • complete mediation – checking permission each time subject requests access to objects.
  • open design – design is not a secret, implementation of safeguard is. (ex: cryptography algorithms are open but the keys used are secret)
  • least common mechanism – minimize the amount of mechanism common to more than one user and depended on by all users. Every shared mechanism (especially one involving shared variables) represents a potential information path between users and must be designed with great care to be sure it does not unintentionally compromise security.
  • psychological acceptability – accessibility to resources should not be inhibited by security mechanisms. If security mechanisms hinder the usability or accessibility of resources, then users may opt to turn off those mechanisms.
  • weakest link – attackers are more likely to attack a weak spot in a software system than to penetrate a heavily fortified component.
  • leverage existing components – component reuse have many advantages, including the increasing of efficiency and security. From the security point of view the component reuse is reducing the attack surface.
  • single point of failure – a system design should not be susceptible to a single point of failure.

Security Models

Access Control Models

Access controls define what actions a subject can perform on specific objects.

  • Bell-LaPadula confidentiality model – It is focused on maintaining the confidentiality of objects. Bell-LaPadula operates by observing two rules: the Simple Security Property and the * Security Property.
    • The Simple security property states that there is “no read up:” a subject at a specific classification level cannot read an object at a higher classification level.
    • The * Security Property is “no write down:”a subject at a higher classification level cannot write to a lower classification level.
  • Take-Grant  – systems specify the rights that a subject can transfer to a from another subject or object. The model is based on representation of the controls in forms of directed graphs with the vertices being the subjects and the objects. The edges between them represent the right between the subject and objects. The representation of rights takes the form of {t (take), g (grant), r (read), w (write)}.
  • Role-based Access control – users are assign a set of roles they may perform. The roles are associated to the access permissions necessary to perform the tasks.
  • MAC (Mandatory Access Control) Model – in MAC systems the owner or subject cannot determine whether access is to be granted to another subject; it is the job of the operating system to decide.
  • DAC (Discretionary Access Control) Model – in DAC systems the owner of an object can decide which other subjects may have access to the object what specific access they may have.

Integrity Models

  • Biba integrity model  – (sometimes referred as Bell-LaPadula upside down) was the first formal integrity model.  Biba is the model of choice when integrity protection is vital. The Biba model has two primary rules: the Simple Integrity Axiom and the * Integrity Axiom. 
    • The Simple Integrity Axiom is “no read down:”a subject at a specific classification level cannot read data at a lower classification. This protects integrity by preventing bad information from moving up from lower integrity levels.
    • The * Integrity Axiom is “no write up:”a subject at a specific classification level cannot write to data at a higher classification. This protects integrity by preventing bad information from moving up to higher integrity levels.
  • Clark-Wilson  –  (this is an informal model) that protects integrity by requiring subjects to access objects via programs. Because the programs have specific limitations to what they can and cannot do to objects, Clark-Wilson effectively limits the capabilities of the subject.Clark-Wilson uses two primary concepts to ensure that security policy is enforced; well-formed transactions and Separation of Duties.

Information Flow Models

Information in a system must be protected when at rest, in transit and in use.

  • The Chinese Wall model – designed to avoid conflicts of interest by prohibiting one person, such as a consultant, from accessing multiple conflict of interest categories (CoIs). The Chinese Wall model requires that CoIs be identified so that once a consultant gains access to one CoI, they cannot read or write to an opposing CoI.


Risk Management


  • risk – possibility of suffering harm or loss
  • residual risk – risk that remains after a control was added to mitigate the initial risk.
  • total risk – the sum of all risks associated with an asset.
  • asset – resource an organization needs to conduct his business.
  • threat – circumstance or event with the potential to cause harm to an asset.
  • vulnerability – any characteristic if an asset that can be exploited by a threat to cause harm.
  • attack – attempting to use a vulnerability.
  • impact – loss resulting when a threat exploits a vulnerability.
  • mitigate – action taken to reduce the likelihood of a threat.
  • control – measure taken to detect, prevent or mitigate the risk associated with a threat.
  • risk assessment – process of identifying risks and mitigating actions.
  • qualitative risk assessment – subjectively determining the impact of an event that effects assets.
  • quantitative risk assessment –  objectively determining the impact of an event that effects assets.
  • single loss expectation (SLE) – linked to the quantitative risk assessment, it represents the monetary loss or impact of each occurrence of a threat.
    • SLE = asset value * exposure factor
  • exposure factor – linked to the quantitative risk assessment, is a measure of the magnitude of a loss.
  • annualized rate of occurrence (ARO) – linked to the quantitative risk assessment, is the frequency with an event is expected to occur on an annualized basis.
    • ARO = number of events / number of years
  • annualized loss of expectancy (ALE) – linked to the quantitative risk assessment, it represents how much an event is expected to cost per year.
    • ALE = SLE * ARO

Types of risks:

  • Business Risks:
    • fraud
    • regulatory
    • treasury management
    • revenue management
    • contract management
  • Technology Risks:
    • security
    • privacy
    • change management

Types of controls

Controls can be classified on types of actions they perform. Three classes of controls exist:

  • administrative
  • technical
  • physical

For each of these classes, there are four types of controls:

  • preventive (deterrent) – used to prevent the vulnerability
  • detective – used to detect the presence of an attack.
  • corrective (recovery) – correct a system after a vulnerability is exploited and an impact has occurred; backups are  a common form of corrective controls.
  • compensation – designed to act when a primary set of controls has failed.

Risk management models

General risk management model

The steps contained in a general risk management model:

  1. Asset identification – identify and clarify all the assets, systems and processes that need to be protected.
  2. Threat assessment – identify the threats and vulnerabilities associated with each asset.
  3. Impact determination and qualification
  4. Control design and evaluation – determine which controls to put in place to mitigate the risks.
  5. Residual risk management – evaluate residual risks to identify where additional controls are needed.

Risk management model proposed by Software Engineering Institute

SEI model steps :

  1. Identity – enumerate potential risks.
  2. Analyze – convert the risk data gather into information that can be used to make decisions.
  3. Plan – decide the actions to take to mitigate them.
  4. Track – monitor the risks and mitigations plans.
  5. Control – make corrections for deviations from the risk mitigation plan.

Security Policies and Regulations

One of the most difficult aspects of prosecution of computer crimes is attribution. Meeting the burden of proof requirement in criminal proceedings, beyond a reasonable doubt, can be difficult given an attacker can often spoof the source of the crime or can leverage different systems under someone else’s control.

Intellectual property

Intellectual property is protected by the U.S law under one of four classifications:

  • patents – Patents provide a monopoly to the patent holder on the right to use, make, or sell an invention for a period of time in exchange for the patent holder’s making the invention public.
  • trademarks – Trademarks are associated with marketing: the purpose is to allow for the creation of a brand that distinguishes the source of products or services.
  • copyrights – represents a type of intellectual property that protects the form of expression in artistic, musical, or literary works, and is typically denoted by the circle c symbol. Software is typically covered by copyright as if it were a literary work. Two important limitations on the exclusivity of the copyright holder’s monopoly exist: the doctrines of first sale and fair use. The first sale doctrine allows a legitimate purchaser of copyrighted material to sell it to another person. If the purchasers of a CD later decide that they no longer cared to own the CD, the first sale doctrine gives them the legal right to sell the copyrighted material even though they are not the copyright holders.
  • trade secrets – business-proprietary information that is important to an organization’s ability to compete. Software source code or firmware code are examples of computer-related objects that an organization may protect as trade secrets.

Privacy and data protection laws

Privacy and data protection laws are enacted to protect information collected and maintained on individuals from unauthorized disclosure or misuse.

Several important pieces of privacy and data protection legislation include :

  • U.S. Federal Privacy Act of 1974 – protects records and information maintained by U.S. government agencies about U.S. citizens and lawful permanent residents.
  •  U.S. Health Insurance Portability and Accountability Act (HIPAA) of 1996 – seeks to guard protected health information from unauthorized use or disclosure.
  • Payment Card Industry Data Security Standard (PCI-DSS) – the goal is to ensure better protection of card holder data through mandating security policy, security devices, control techniques and monitoring of systems and networks.
  • U.S. Gramm-Lech-Bliley Financial Services Modernization Act (GLBA) – requires financial institutions to protect the confidentiality and integrity of consumer financial information.
  • U.S. Sarbanes-Oxley Act of 2002 (SOX) – the primary goal of SOX is to ensure adequate financial disclosure and financial auditor independence.

Secure Software Architecture – Security Frameworks

  • COBIT (Control Objectives for Information and Related Technology)– assist management in bringing the gap between control requirements, technological issues and business risks.
  • COSO (Committee of Sponsoring Organizations of the Treadway Commission) – COSO has established a Enterprise Risk Management -Integrated Framework against which companies and organizations may assess their control systems.
  • ITIL (Information Technology Infrastructure Library) – describes a set of practices focusing on aligning IT services with business needs.
  • SABSA (Sherwood Applied Business Security Architecture) – framework and methodology for developing risk-driven enterprise information security architecture.
  • CMMI (Capability Maturity Model Integration) – process metric model that rates the process maturity of an organization on a 1 to 5 scale.
  • OCTAVE (Operationally Critical Threat, Asset and Vulnerability Evaluation) – suite of tools, techniques and methods for risk-based information security assessment.


Software Development Methodologies

Secure Development Lifecycle Components

  • software team awareness and education – all team members should have appropriate training. The key element of team awareness and education is to ensure that all the members are properly equipped with the correct knowledge.
  • gates and security requirements – the term gates it signifies a condition that one must pass through. To pass the security gate a review of the appropriate security requirements is conducted.
  • threat modeling – design technique used to communicate information associated with a threat throughout the development team (for more infos’ you could check my other ticket : threat modeling for mere mortals).
  • fuzzing – a test technique where the tester applies a series of inputs to an interface in an automated fashion and examines the output for undesired behaviors.
  • security reviews – process to ensure that the security-related steps are being carried out and not being short-circuited.

Software Development Models

  • waterfall model – is a linear application development model that uses rigid phases; when one phase ends, the next begins.
  • spiral model – repeats steps of a project, starting with modest goals, and expanding outwards in ever wider spirals (called rounds). Each round of the spiral constitutes a project, and each round may follow traditional software development methodology such as Modified Waterfall. A risk analysis is performed each round.
  • prototype model – working model of software with some limited functionality. Prototyping is used to allow the users evaluate developer proposals and try them out before implementation.
  • agile model
    • Scrum  – contain small teams of developers, called the Scrum Team. They are supported by a Scrum Master, a senior member of the organization who acts like a coach for the team. Finally, the Product Owner is the voice of the business unit.
    • Extreme Programming (XP) – method that uses pairs of programmers who work off a detailed specification.

Microsoft Security Development Lifecycle

SDL is software development process designed ti enable development teams to build more secure software and address security compliance requirements.

SDC is build around the following three elements:

  • (security) by design – the security thinking is incorporated as part of design process.
  • (security) by default – the default configuration of the software is by design as secure as possible.
  • (security) in deployment – security and privacy elements are properly understood and managed through the deployment process.

SDL components:

  • training   security training for all personnel, targeted to their responsibility associated with the development effort.
  • requirements
    • establishment of the security and privacy requirements for the software.
    • creation of quality gates ans bug bars. Defining minimum acceptable levels of security and privacy quality at the start helps a team understand risks associated with security issues, identify and fix security bugs during development, and apply the standards throughout the entire project.Setting a meaningful bug bar involves clearly defining the severity thresholds of security vulnerabilities (for example, no known vulnerabilities in the application with a “critical” or “important” rating at time of release) and never relaxing it once it’s been set.
    • development of security and privacy risk assessment. Examining software design based on costs and regulatory requirements helps a team identify which portions of a project will require threat modeling and security design reviews before release and determine the Privacy Impact Rating of a feature, product, or service.
  • design – establish design requirements, perform attack/surface analysis/reduction and use threat modeling.
  • implementation – application of secure coding practices and the use of static program checkers to find common errors.
  • verification – perform dynamic analysis (tools that monitor application behavior for memory corruption, user privilege issues, and other critical security problems), fuzz testing and conduct attack surface review.
  • release – conduct final security review and create an incident response plan.
  • response – execute incident response plan.

(My) CEH cheat sheet

This is the small (and I hope) useful cheat sheet for the CEH V8 certification.

This is strongly inspired from the CEH Certified Ethical Hacker Bundle, Second Edition book.


“Bit flipping” is one form of an integrity attack. In bit flipping, the attacker isn’t interested in learning the entirety of the plaintext message.

There are three main phases to a pen test: preparation, assessment, and conclusion.

Black box testing, the ethical hacker has absolutely no knowledge of the TOE. It’s designed to simulate an outside, unknown attacker, takes the most amount of time to complete.

White box testing, pen testers have full knowledge of the network, system, and infrastructure they’re targeting.

Gray box testing, is also known as partial knowledge testing. What makes this different from black box testing is the assumed level of elevated privileges the tester has. Whereas black box testing is generally done from the network administration level, gray box testing assumes only that the attacker is an insider.

Attack Types

EC Council broadly defines four attack types categories:

  • Operating system attacks Generally speaking, these attacks target the common mistake many people make when installing operating systems— accepting and leaving all the defaults. Things like administrator accounts with no passwords, all ports left open, and guest accounts (the list could go on forever) are examples of settings the installer may forget about.
  • Application-level attacks These are attacks on the actual programming codes of an application. Although most people are very cognizant of securing their OS and network, it’s amazing how often they discount the applications running on their OS and network. Many applications on a network aren’t tested for vulnerabilities as part of their creation and, as such, have many vulnerabilities built into them. Applications on a network are a goldmine for most hackers.
  • Shrink-wrap code attacks These attacks take advantage of the built-in code and scripts most off-the-shelf applications come with. These scripts and code pieces are designed to make installation and administration easier, but can lead to vulnerabilities if not managed appropriately.
  • Misconfiguration attacks These attacks take advantage of systems that are, on purpose or by accident, not configured appropriately for security.

An asset is an item of economic value owned by an organization or an individual. Identification of assets within the risk analysis world is the first and most important step.

A threat is any agent, circumstance, or situation that could cause harm or loss to an IT asset.

A vulnerability is any weakness, such as a software flaw or logic design, that could be exploited by a threat to cause damage to an asset.

18 U.S.C § 1029 and 1030

Basically, the law gives the U.S. government the authority to prosecute criminals who traffic in, or use, counterfeit access devices. In short, the section criminalizes the misuse of any number of credentials, including pass- words, PIN numbers, token cards, credit card numbers, and the like.


Symmetric Encryption – The formula for calculating how many key pairs you will need is N (N – 1) / 2 where N is the number of nodes in the network

Symmetric algorithms:

  • DES A block cipher that uses a 56-bit key (with 8 bits reserved for parity); fixed blocked size.
  • 3DES A block cipher that uses a 168-bit key. 3DES (called triple DES) can use up to three keys in a multiple-encryption method.
  • AES (Advanced Encryption Standard) A block cipher that uses a key length of 128, 192, or 256 bits, and effectively replaces DES.
  • IDEA (International Data Encryption Algorithm) A block cipher that uses a 128-bit key.
  • Twofish A block cipher that uses a key size up to 256 bits.
  • Blowfish A fast block cipher, largely replaced by AES, using a 64-bit block size and a key from 32 to 448 bits.
  • RC (Rivest Cipher) Encompasses several versions from RC2 through RC6. A block cipher that uses a variable key length up to 2,040 bits. RC6, the latest version, uses 128-bit blocks, whereas RC5 uses variable block sizes (32, 64, or 128).

Asymmetric Encryption

Generally: public key = encrypt, private key = decrypt.

Asymmetric algorithms:

  • Diffie-Hellman Developed for use as a key exchange protocol, Diffie- Hellman is used in Secure Sockets Layer (SSL) and IPSec encryption.
  • Elliptic Curve Cryptosystem (ECC) Uses points on an elliptical curve, in conjunction with logarithmic problems, for encryption and signatures. Uses less processing power than other methods, making it a good choice for mobile devices.
  • El Gamal Not based on prime number factoring, this method uses the solving of discrete logarithm problems for encryption and digital signatures.
  • RSA An algorithm that achieves strong encryption through the use of two large prime numbers. Factoring these numbers creates key sizes up to 4,096 bits. RSA can be used for encryption and digital signatures and is the modern de facto standard.

Hash algorithms:

  • MD5 (Message Digest algorithm) Produces a 128-bit hash value output, expressed as a 32-digit hexadecimal.
  • SHA-1 Developed by the NSA (National Security Agency), SHA-1 produces a 160-bit value output, and was required by law for use in U.S. government applications.
  • SHA-2 Developed by the NSA, actually holds four separate hash functions that produce outputs of 224, 256, 384, and 512 bits.

Trust Models

  • web of trust, multiple entities sign certificates for one another.
  • single authority system has a CA at the top that creates and issues certs. Users trust each other based on the CA itself.
  • hierarchical trust system also has a CA at the top (which is known as the root CA), but makes use of one or more intermediate CAs underneath it— known as registration authorities (RAs)—to issue and manage certificates.

Cryptography Attacks:

  • Known plaintext attack In this attack, the hacker has both plaintext and corresponding ciphertext messages—the more, the better. The plaintext copies are scanned for repeatable sequences, which are then compared to the ciphertext versions. Over time, and with effort, this can be used to decipher the key.
  • Ciphertext-only attack In this attack, the hacker gains copies of several messages encrypted in the same way (with the same algorithm). Statistical analysis can then be used to reveal, eventually, repeating code, which can be used to decode messages later on.
  • Replay attack Most often performed within the context of a man-in-the- middle attack. The hacker repeats a portion of a cryptographic exchange in hopes of fooling the system into setting up a communications channel. The attacker doesn’t really have to know the actual data (such as the password) being exchanged, he just has to get the timing right in copying and then replaying the bit stream. Session tokens can be used in the communications process to combat this attack.

A digital certificate is an electronic file that is used to verify a user’s identity, providing non-repudiation throughout the system.

  • Version This identifies the certificate format.. The most common version in use is 1.
  • Serial Number Fairly self-explanatory, the serial number is used to uniquely identify the certificate itself.
  • Subject Whoever or whatever is being identified by the certificate.
  • Algorithm ID (or Signature Algorithm) Shows the algorithm that was used to create the digital signature.
  • Issuer Shows the entity that verifies the authenticity of the certificate. The issuer is the one who creates the certificates.
  • Valid From and Valid To These fields show the dates the certificate is good through.
  • Key Usage Shows for what purpose the certificate was created.
  • Subject’s Public Key A copy of the subject’s public key is included in the digital certificate.
  • Optional fields These fields include Issuer Unique Identifier, Subject Alternative Name, and Extensions.


FOR ECCouncil Vulnerability Research is part of the reconnaissance.

Difference in definition between reconnaissance and footprinting:

For many, recon is more of an overall, over-arching term for gathering information on targets, whereas footprint- ing is more of an effort to map out, at a high level, what the landscape looks like. They are interchangeable terms in CEH parlance, but if you just remember that footprinting is part of reconnaissance.


DNS is using port 53; Name lookups generally use UDP, whereas zone transfers use TCP.

DNS record types:

  • SRV- Service Defines the host name and port number of servers providing specific services, such as a Directory Services server.
  • SOA – Start Of Authority This record identifies the primary name server for the zone.The SOA record contains the host name of the server responsible for all DNS records within the namespace, as well as the basic properties of the domain.
  • PTR – Pointer Maps an IP address to a host name (providing for reverse DNS lookups).You don’t absolutely need a PTR record for every entry in your DNS namespace, but these are usually associated with e-mail server records.
  • NS – Name Server This record defines the name servers within your namespace.These servers are the ones that respond to your clients’ requests for name resolution.
  • MX -Mail Exchange This record identifies your e-mail servers within your domain.
  • CNAME – Canonical Name This record provides for domain name aliases within your zone. For example, you may have an FTP service and a web service running on the same IP address. CNAME records could be used to list both within DNS for you.
  • A – Address This record maps an IP address to a host name, and is used most often for DNS lookups.

DNS Footprinting tools: whois, nslookup, dig

Scanning and Enumeration

Relevant ICMP Message Types

  • 0: Echo Reply – Answer to a Type 8 Echo Request
  • 3: Destination Unreachable

Error message indicating the host or network cannot be reached.


0—Destination network unreachable

1—Destination host unreachable

6—Network unknown

7—Host unknown

9—Network administratively prohibited 10—Host administratively prohibited

13—Communication administratively prohibited

  • 4: Source Quench A congestion control message
  • 5: Redirect Sent when there are two or more gateways available for the sender to use, and     the best route available to the destination is not the configured default gateway.


0—Redirect datagram for the network

1—Redirect datagram for the host

  • 8: ECHO Request A ping message, requesting an Echo reply
  • 11:Time Exceeded The packet took too long to be routed to the destination (Code 0 is TTL expired).

The port numbers range from 0 to 65,535 and are split into three different groups:

  • Well-known: 0–1023
  • Registered: 1024–49151
  • Dynamic: 49152–65535

Some of the more important well-known port numbers to remember are:

  • FTP (20/21)
  • Telnet (23)
  • SMTP (25)
  • DNS (53),
  • POP3 (110)
  • NetBIOS (137–139)
  • SNMP (161/162)

The TCP header flags are:

  • URG (Urgent) When this flag is set, it indicates the data inside is being sent out of band.
  • ACK (Acknowledgment) This flag is set as an acknowledgment to SYN flags. This flag is set on all segments after the initial SYN flag.
  • PSH (Push) This flag forces delivery of data without concern for any buffering.
  • RST (Reset) This flag forces a termination of communications (in both directions).
  • SYN (Synchronize) This flag is set during initial communication establishment. It indicates negotiation of parameters and sequence numbers.
  • FIN (Finish) This flag signifies an ordered close to communications.

Nmap is the de-facto tool for footprinting networks. It is capable of finding live hosts, access points, fingerprinting

operating systems, and verifying services. It also has important IDS evasion capabilities.

nmap <scan options> <target>

-sA ACK scan

-sI FIN scan

-sL IDLE scan

-sN DNS scan

-sO NULL scan

-sP Ping scan

-sR RPC scan

-sS SYN scan

-sT TCP connect scan

-sW Window scan

-sX XMAS tree scan

-PI ICMP ping

-Po No ping

-PS SYN ping

-PT TCP ping

-oN normal output

-oX XML output

-T0 slowest – T4 fastest

Seven generic scan types for port scanning:

  • TCP Connect Runs through a full connection (three-way handshake) on all ports. Easiest to detect, but possibly the most reliable. Open ports will respond with a SYN/ACK, closed ports with a RST/ACK.
  • SYN Known as a “half-open scan.” Only SYN packets are sent to ports (no completion of the three-way handshake ever takes place). Open ports will respond with a SYN/ACK, closed ports with a RST/ACK.
  • FIN scans run the communications setup in reverse, sending a packet with the FIN flag set. Closed ports will respond with RST, whereas open ports won’t respond at all.
  • XMAS A Christmas scan is so named because the packet is sent with multiple flags (FIN, URG, and PSH) set. Closed ports will respond with RST, whereas open ports won’t respond at all
  • ACK Used mainly for Unix/Linux-based systems. Open ports will send RST, closed ports, no answer
  • IDLE Uses a spoofed IP address to elicit port responses during a scan. Designed for stealth, this scan uses a SYN flag and monitors responses as with a SYN scan.
  • NULL Almost the opposite of the XMAS scan. The NULL scan sends packets with no flags set. Responses will vary, depending on the OS and version, but NULL scans are designed for Unix/Linux machines.

War dialing is a process by which an attacker dials a set of phone numbers specifi- cally looking for an open modem.

War driving used to refer to, quite literally, driving around in a car looking for open access points. In the ethical hacking realm, it still indicates a search for open WAP

Simple Network Management Protocol was designed to manage IP-enabled devices across a network. As a result, if it is in use on the subnet, you can find out loads of information with properly formatted SNMP requests. Later versions of SNMP make this a little more difficult, but plenty of systems out there are still using the protocol in version 1.

Sniffers and Evasion

All Peoples Seems To Need Data Processing – mnemonic phrase to remember the layers.

  • ISO/OSI layers

Application – data

Presentation – data

Session   – data

Transport – segment

Network – packet

Data     -frames

Physical – byes

ISO/OSI to TCP/IP mapping(3 1 1 2)

  • TCP/IP Model layers




Network Access

The MAC address that is burned onto a NIC is actually made of two sections.The first half of the address, 3 bytes (24 bits), is known as the Organizational Unique Identifier, and is used to identify the card manufacturer.The second half is a unique number burned in at manufacturing, to ensure no two cards on any given subnet will have the same address.

MAC Spoofing Set the MAC address of a NIC to the same value as another

MAC Flooding Overwhelm the CAM (content addressable memory) table of the switch so it coverts to hub mode

ARP Poisoning Inject incorrect information into the ARP caches of two or more endpoints.


Snort rule:

alert tcp !HOME_NET any -> $HOME_NET 31337 (msg :"BACKDOOR ATTEMPT-Backorifice")

If you happen to come across a packet from any address that is not my home network, using any source port, intended for an address within my home network on port 31337, alert me with the message ‘BACKDOOR ATTEMPT-Back- orifice.’”

Span port = port mirroring

False negative – when an IDS reports a particular stream as clean but it’s not

Wireshark display filters

Display filters work basically like: proto.field operator value

Analyse the following examples:

tcp.flags == 0x29
ip.addr !=
tcp.port eq 25 or icmp
ip.src== and ip.dst==
http.request.uri matches "login.html"

Tcpdump syntax:

tcmdump flag(s) interface

Attacking a System

EC-Council rules for the passwords:

  • The password must not contain any part of the user’s name. For example, a password of [email protected]!” wouldn’t work for the CEH exam, because you can clearly see my name there.
  • The password must have a minimum of eight characters. Eight is okay. Nine is better. Seven? Not so good.
  • The password must contain characters from at least three of the four major components of complexity—that is, special symbols (such as @&*#$), uppercase letters, lowercase letters, and numbers. [email protected] contains all four, whereas use8chars uses only two.

LM Hashing – 7 spaces hashed = AAD3B435B51404EE

Four main attack types are defined within CEH.

  • passive online attack basically amounts to sniffing a wire in the hopes of either intercepting a password in clear text or attempting a replay or man-in- the-middle (MITM) attack.
  • active online, occurs when the attacker begins simply trying passwords—guessing them, for lack of a better word
  • offline attacks occur when the hacker steals a copy of the password file (remember our discussion on the SAM file earlier?) and works the cracking efforts on a separate system.
  • non-electronic = the social engineering.

sidejacking. The idea is to steal the cookies exchanged between two systems and ferret out which one to use as a replay-style attack

Social Engineering and Physical Security

Human-Based Attacks

  • Dumpster diving
  • Impersonation
  • Technical support
  • Shoulder surfing
  • Tailgating and piggybacking

Computer-Based Attacks

  • phishing.

Types of Social Engineers

  • Insider Associates Have limited authorized access, and escalate privileges from there.
  • Insider Affiliates Are insiders by virtue of an affiliation, they spoof the identity of the insider.
  • Outsider Affiliates Are nonͲtrusted outsiders that use an access point that was left open.

Physical Security

Three major categories of physical security measures:

  • Physical measures include all the things you can touch, taste, smell, or get shocked by. For example, lighting, locks, fences, and guards with Tasers are all physical measures.
  • Technical measures are a little more com- plicated. These are measures taken with technology in mind, to protect explicitly at the physical level. For example, authentication and permissions may not come across as phys- ical measures, but if you think about them within the context of smart cards and bio- metrics, it’s easy to see how they should become technical measures for physical security.
  • Operational measures are the policies and procedures you set up to enforce a security-minded operation.

Web-Based Hacking

This dot-dot-slash attack is also known as a variant of “Unicode” or unvalidated input attack.

SQL injection attacks types:

  • Union query The thought here is to make use of the UNION command to return the union of your target database with one you’ve crafted to steal data from it.
  • Tautology An overly complex term used to describe the behavior of a database system when deciding whether or not a statement is true. Because user IDs and passwords are often compared, and the “true” measure allows access, if you trick the database by providing something that is already true (1 does, indeed, equal 1), then you can sneak by.
  • Blind SQL injection This occurs when the attacker knows the database is susceptible to injection, but the error messages and screen returns don’t come back to the attacker. Because there’s a lot of guesswork and trial and error, this attack takes a long while to pull off.
  • Error-based SQL injection This isn’t necessarily an attack so much as an enumeration technique. The objective is to purposely enter poorly constructed statements in an effort to get the database to respond with table names and other information in its error messages.

The buffer overflow attack categories are as follows:

  • Stack This idea comes from the basic premise that all program calls are kept in a stack and executed in order. If you affect the stack with a buffer overflow, you can perhaps change a function pointer or variable to allow code execution.
  • Heap Also referred to as heap overflow, this attack takes advantage of the memory “on top of” the application, which is allocated dynamically at runtime. Because this memory usually contains program data, you can cause the application to overwrite function pointers.
  • NOP Sled A NOP sled makes use of a machine instruction called “no-op.” In the attack, a hacker sends a large number of NOP instructions into the buffer, appending command code instruction at the end. Because this attack is so common, most IDSs protect against it.

Dangerous Functions for buffer overflows

The following functions are dangerous because they do not check the size of the destination buffers:





Wireless Network hacking

802.11 Specifications

Spec   Distance Speed Freq

802.11a 30M     54Mbps   5Ghz

802.11b 100M   11Mbps 2.4Ghz

802.11g 100M   54Mbps 2.4Ghz

802.11n 125M   100Mbps+ 2.4Ghz, 5Ghz


WEP Uses RC4 for the stream cipher with a 24b initialization vector

Key sizes are 40b or 104b

WPA Uses RC4 for the stream cipher but supports longer keys; 48 bits IV

WPA/TKIP Changes the IV with each frame and includes key mixing

WPA2 Uses AES as the stream cipher and includes all the features of TKIP; 48 bits IV.


Rogue APs (evil twins) may also be referenced as a “mis- association” attack.


Bluetooth attackes :

Bluesmacking is simply a denial-of-service attack against a device.

Bluejacking consists of sending unsolicited messages to, and from, mobile devices.

Bluesniffing is exactly what it sounds like, and, finally.

Bluescarfing is the actual theft of data from a mobile device.

Trojans and Other Attacks

Windows will automatically run everything located in Run, RunServices, RunOnce, and RunServicesOnce

Virus types:

  • Boot sector virus Also known as a system virus, this virus type actually moves the boot sector to another location on the hard drive, forcing the virus code to be executed first. They’re almost impossible to get rid of once you get infected. You can re-create the boot record—old-school fdisk or mbr could do the trick for you—but it’s not necessarily a walk in the park.
  • Shell virus Working just like the boot sector virus, this virus type wraps itself around an application’s code, inserting its own code before the application’s. Every time the application is run, the virus code is run first.
  • Multipartite virus Attempts to infect both files and the boot sector at the same time. This generally refers to a virus with multiple infection vectors. This link describes one such DOS-type virus: http://www.f-secure.com/v-descs/ neuroqui.shtml. It was multipartite, polymorphic, retroviral, boot sector, and generally a pretty wild bit of code.
  • Macro virus Usually written with VBA (Visual Basic for Applications), this virus type infects template files created by Microsoft Office—normally Word and Excel. The Melissa virus was a prime example of this.
  • Polymorphic code virus This virus mutates its code using a built-in polymorphic engine. These viruses are very difficult to find and remove because their signatures constantly change.
  • Metamorphic virus This virus type rewrites itself every time it infects a new file.

DOS attack types:

  • SYN attack The hacker will send thousands upon thousands of SYN packets to the machine with a false source IP address. The machine will attempt to respond with a SYN/ACK but will be unsuccessful (because the address is false). Eventually, all the machine’s resources are engaged and it becomes a giant paperweight.
  • SYN flood In this attack, the hacker sends thousands of SYN packets to the target, but never responds to any of the return SYN/ACK packets. Because there is a certain amount of time the target must wait to receive an answer to the SYN/ACK, it will eventually bog down and run out of available connections.
  • ICMP flood Here, the attacker sends ICMP Echo packets to the target with a spoofed (fake) source address. The target continues to respond to an address that doesn’t exist and eventually reaches a limit of packets per second sent.
  • Application level A simple attack whereby the hacker simply sends more “legitimate” traffic to a web application than it can handle, causing the system to crash.
  • Smurf The attacker sends a large number of pings to the broadcast address of the subnet, with the source IP spoofed to that of the target. The entire subnet will then begin sending ping responses to the target, exhausting the resources there. A fraggle attack is similar, but uses UDP for the same purpose.
  • Ping of death In the ping of death, an attacker fragments an ICMP message to send to a target. When the fragments are reassembled, the resultant ICMP packet is larger than the maximum size and crashes the system.

(My) CISSP Notes – Bibliography

This is the last ticket from/for “(My) CISSP Notes” and will contains links to the materials that I used for the preparation of the exam.


  • CISSP study guide – This was my main source of information.
  • CISSP for dummies – This was my second source of information; very easy to read and understand but not sufficient to pass the exam.
  • 11th Hour CISSP: Study guide – This is a short version of the CISSP study guide . I use it for a quick review the last few days before the exam.
  • CISSP Boxed Set – This box set contains a study guide and a book with practice exams. I used the study guide only punctually for specific topics and I found it very complete. I tried at the beginning the use it as the main source of information but the main problem is the huge quantity of information (1400 pages).

Practice Exams

Audio Postcasts

  • McGraw-Hill Education CISSP Podcasts – The podcasts are covering all the domains and are of quite good (audio) quality.  If you don’t have the time to listen everything then you could choose the listen only the review podcasts containing only the most important information.

(My) CISSP Notes – Security Operations

Note: This notes were made using the following books: “CISPP Study Guide” and “CISSP for dummies”.

Operations Security is concerned with threats to a production operating environment.

So operations security is about people, data, media, hardware, and the threats associated with each of these in a production environment.

Administrative security

One fundamental aspect of operations security is ensuring that controls are in place to inhibit people either inadvertently or intentionally compromising the confidentiality, integrity, or availability of data or the systems and media holding that data. Administrative Security provides the means to control people’s operational access to data.

Administrative personnel controls :

  • least privilege – the principle of least privilege dictates that persons have no more than the access that is strictly required for the performance of their duties.
  • need to know – only people with a valid need to know certain information in order to perform their job functions, should have access to that information.An extension to the principle of least privilege in MAC environments is the concept of compartmentalizationCompartmentalization, a method for enforcing need to know, goes beyond the mere reliance upon clearance level and necessitates simply that someone requires access to information.
  • separation of duties –  prescribes that multiple people are required to complete critical or sensitive transactions.The goal of separation of duties is to ensure that in order for someone to be able to abuse their access to sensitive data or transactions; they must convince another party to act in concert. Collusion is the term used for the two parties conspiring to undermine the security of the transaction.
  • rotation of duties – also known as job rotation or rotation of responsibilities, provides an organization with a means to help mitigate the risk associated with any one individual having too many privileges.Rotation of duties simply requires that critical functions or responsibilities are not continuously performed by the same single person without interruption.
  • mandatory leave – an additional operational control that is closely related to rotation of duties is that of mandatory leave, also known as forced vacation.
  • non-disclouse agreement (NDA) – is a work-related contractual agreement that ensures that, prior to being given access to sensitive information or data, an individual or organization appreciates their legal responsibility to maintain the confidentiality of sensitive information.
  • background checks – also known as background investigations or preemployment screening; are an additional administrative control commonly employed by many organizations.

Sensitive information/media security

Wherever the data exists, there must be processes that ensure the data is not destroyed or inaccessible (a breach of availability), disclosed, (a breach of confidentiality) or altered (a breach of integrity).

Perhaps the most important step in media security is the process of locating sensitive information, and labeling or marking it as sensitive.

People handling sensitive media should be trusted individuals who have been vetted by the organization.

When storing sensitive information, it is preferable to encrypt the data. Encryption of data at rest greatly reduces the likelihood of the data being disclosed in an unauthorized fashion due to media security issues.

The term data remanence is important to understand when discussing media sanitization and data destruction. Data remanence is data that persists beyond noninvasive means to delete it.

Wiping, also called overwriting or shredding, writes new data over each bit or block of file data.

By introducing an external magnetic field through use of a degausser, the data on magnetic storage media can be made unrecoverable.

Asset management

  • Patch management – One of the most basic, yet still rather difficult, tasks associated with maintaining strong system security configuration is patch management, the process of managing software updates.
  • Vulnerability management – Vulnerability scanning is a way to discover poor configurations and missing patches in an environment. While it might seem obvious, it bears mentioning that vulnerability scanning devices are only capable of discovering the existence of known vulnerabilities. The term vulnerability management is used rather than just vulnerability scanning to emphasize the need for management of the vulnerability information.
  • Change management – In order to maintain consistent and known operational security, a regimented change management or change control process needs to be followed. The purpose of the change control process is to understand, communicate, and document any changes with the primary goal of being able to understand, control, and avoid direct or indirect negative impact that the change might impose.

Continuity of operation

Three basic types of backups exist:

  • full backup – is the easiest to understand of the types of backup; it simply is a replica of all allocated data on a hard disk. Full backups contain all of the allocated data on the hard disk, which makes them simple from a recovery standpoint in the event of a failure.
  • incremental backup – one alternative to exclusively relying upon full backups is to leverage incremental backups. Incremental backups only archive files that have changed since the last backup of any kind was performed. Since fewer files are backed up, the time to perform the incremental backup is greatly reduced.
  • differential backup – while the incremental backup only archived those files that had changed since any backup, the differential method will back up any files that have been changed since the last full backup.

Redundant array of inexpensive disks (RAID)

The goal of a Redundant Array Inexpensive Disks (RAID) is to help mitigate the risk associated with hard disk failures.

Three terms that are important to understand with respect to RAID are:

  • mirroring – is the most obvious and basic of the fundamental RAID concepts, and is simply used to achieve full data redundancy by writing the same data to multiple hard disks.
  • striping – is a RAID concept that is focused on increasing the read and write performance by spreading data across multiple hard disks. With data being spread amongst multiple disk drives, reads and writes can be performed in parallel across multiple disks rather than serially on one disk.
  • parity – is a means to achieve data redundancy without incurring the same degree of cost as that of mirroring in terms of disk usage and write performance.

RAID 0: Striped Set As is suggested by the title, RAID 0 employs striping to increase the performance of read and writes. By itself, striping offers no data redundancy so RAID 0 is a poor choice if recovery of data is the reason for leveraging RAID.

RAID 1: Mirrored Set This level of RAID is perhaps the simplest of all RAID levels to understand. RAID 1 creates/writes an exact duplicate of all data to an additional disk. The write performance is decreased, though the read performance can see an increase.

RAID 2: Hamming Code RAID 2 is not considered commercially viable for hard disks and is not used. This level of RAID would require either 14 or 39 hard disks and a specially designed hardware controller, which makes RAID 2 incredibly cost prohibitive. RAID 2 is not likely to be tested.

RAID 3: Striped Set with Dedicated Parity (byte level) Striping is desirable due to the performance gains associated with spreading data across multiple disks. However, striping alone is not as desirable due to the lack of redundancy. With RAID 3 data, at the byte level, is striped across multiple disks, but an additional disk is leveraged for storage of parity information, which is used for recovery in the event of a failure.

RAID 4: Striped Set with Dedicated Parity (block level) RAID 4 provides the exact same configuration and functionality as that of RAID 3, but stripes data at the block, rather than byte, level.

RAID 5: Striped Set with Distributed Parity One of the most popular RAID configurations is that of RAID 5, Striped Set with Distributed Parity. Again with RAID 5 there is a focus on striping for the performance increase it offers, and RAID 5 leverages a block level striping. Like RAIDs 3 and 4, RAID 5 writes parity information that is used for recovery purposes. However, unlike RAIDs 3 and 4, which require a dedicated disk for parity information, RAID 5 distributes the parity information across multiple disks.

RAID 6: Striped Set with Dual Distributed Parity While RAID 5 accommodates the loss of any one drive in the array, RAID 6 can allow for the failure of two drives and still function. This redundancy is achieved by writing the same parity information to two different disks.

System redundancy

The most common example of this in-built redundancy is systems or devices which have redundant onboard power in the event of a power supply failure. In addition to redundant power, it is also common to find redundant network interface cards (NICs), as well as redundant disk controllers.

Some applications and systems are so critical that they have more stringent uptime requirements than can be met by standby redundant systems, or spare hardware. These systems and applications typically require what is commonly referred to as a high-availability (HA) or failover cluster. A high-availability cluster employs multiple systems that are already installed, configured, and plugged in, such that if a failure causes one of the systems to fail then the other can be seamlessly leveraged to maintain the availability of the service or application being provided.

Incident response management

Incident handling or incident response are the terms most commonly associated with how an organization proceeds to identify, react, and recover from security incidents.

Computer Security Incident Response Team (CSIRT) is a term used for the group that is tasked with monitoring, identifying, and responding to security incidents.

Phases of incident responses :

  • detection – one of the most important steps in the incident response process is the detection phase. Detection is the phase in which events are analyzed in order to determine whether these events might comprise a security incident.
  • containment – is the point at which the incident response team attempts to keep further damage from occurring as a result of the incident.This phase is also typically where a binary (bit by bit) forensic backup is made of systems involved in the incident.
  • eradication – involves the process of understanding the cause of the incident so that the system can be reliably cleaned and ultimately restored to operational status later in the recovery phase.
  •  recovery – involves cautiously restoring the system or systems to operational status.
  • reporting – is the one most likely to be neglected in immature incident response programs. This fact is unfortunate because the reporting phase, if done right, is the phase that has the greatest potential to effect a positive change in security posture. The goal of the reporting phase is to provide a final report on the incident, which will be delivered to management.

(My) CISSP Notes – Physical Security

Note: This notes were made using the following books: “CISPP Study Guide” and “CISSP for dummies”.

Physical (Environmental) security protects the Confidentiality, Integrity and Availability  of physical assets: people, buildings, systems, and data. The CISSP® exam considers human safety as the most critical concern of this domain, which trumps all other concerns.

Physical security protects against threats such as unauthorized access and disasters, both man-made and natural. Controls used in this domain are primarily physical (such as locks, fences, guards, etc.); administrative controls (such as policy and procedures) and technical (such as biometrics) are also used.

Physical access control

Physical access control consists of the systems and techniques used to restrict access to a security perimeter and provide boundary protection.

Types of Vehicle Gates :

  • class 1 – residential (home use)
  • class 2 – commercial/general access (parking garage)
  • class 3 – industrial/limited access
  • class 4 – restricted access

A traffic bollard is a strong post designed to stop a car.

Lock picking is the art of opening a lock without a key.

The master key opens any lock for a given security zone in a building.

The core key is used to remove the lock core in interchangeable core locks (where the lock core may be easily removed and replaced with another core).

A smart card is physical access control device which is often used for electronic locks, credit card purchases, or dual-factor authentication systems.

A magnetic stripe card contains a magnetic stripe which stores information.

A mantrap is a preventive physical control with two doors. The first door must close and lock before the second door may be opened. Each door typically requires a separate form of authentication to open.

Turnstiles are designed to prevent tailgating by enforcing a “one person per authentication” rule, just as they do in subway systems.

Technical controls

Technical control include monitoring and surveillance, intrusion detection systems and alarms.

Closed Circuit Television (CCTV) is a detective device used to aid guards in detecting the presence of intruders in restricted areas.Key issues include depth of field (the area that is in focus) and field of view (the entire area viewed by the camera). More light allows a larger depth of field because a smaller aperture places more of the image in focus. CCTV displays may display a fixed camera view, autoscan (show a given camera for a few seconds before moving to the next), or multiplexing (where multiple camera feeds are fed into one display).

Ultrasonic, microwave, and infrared motion sensors are active sensors, which means they actively send energy.

If you see the term “intrusion” on the exam, be sure to look for the context (human or network-based).

Door hinges should face inward, or be otherwise protected. Externally-facing hinges that are not secured pose a security risk: attackers can remove the hinge pins with a hammer and screwdriver, allowing the door to be opened from the hinge side.

Use of simple glass windows in a secure perimeter requires a compensating control such as window burglar alarms.

Environmental and life safety controls

Environmental controls are designed to provide a safe environment for personnel and equipment. Power, HVAC, and fire safety are considered environmental controls.

The following are common types of electrical faults:

  •  Blackout: prolonged loss of power
  • Brownout: prolonged low voltage
  • Fault: short loss of power
  • Surge: prolonged high voltage
  • Spike: temporary high voltage
  • Sag: temporary low

Heat detectors, flame detectors, and smoke detectors provide three methods for detecting fire.

The two primary evacuation roles are safety warden and meeting point leader.

Classes of Fire and Suppression Agents :

  • Class A  – fires are common combustibles such as wood, paper, etc. This type of fire is the most common and should be extinguished with water or soda acid.
  • Class B  – fires are burning alcohol, oil, and other petroleum products such as gasoline. They are extinguished with gas or soda acid. You should never use water to extinguish a class B fire.
  • Class C  – fires are electrical fires which are fed by electricity and may occur in equipment or wiring. Electrical fires are Conductive fires, and the extinguishing agent must be non-Conductive, such as any type of gas.
  • Class D  – fires are burning metals and are extinguished with dry powder.
  • Class K – fires are kitchen fires, such as burning oil or grease. Wet chemicals are used to extinguish class K fires.

Experts always prefer to prevent a fire rather than extinguish one, and are often generous with their time dedicated to preventive measures.

All fire suppression agents work via four methods (sometimes in combination): reducing the temperature of the fire, reducing the supply of oxygen, reducing the supply of fuel, and interfering with the chemical reaction within fire.

Always consider “hire or ask an expert” as a valid choice for any exam question asking about “the best thing to do.” Do not fall for the engineer’s trap of “I will figure this out on my own.”

Water suppresses fire by lowering the temperature below the kindling point (also called the ignition point). Water is the safest of all suppressive agents, and recommended for extinguishing common combustible fires such as burning paper or wood.

In addition to suppressing fire by lowering temperature, soda acid also has additional suppressive properties beyond plain water: it creates foam which can float on the surface of some liquid fires, starving the oxygen supply.

Extinguishing a fire with dry powder (such as sodium chloride) works by lowering temperature and smothering the fire, starving it of oxygen. Dry powder is primarily used to extinguish metal fires.

Wet chemicals are primarily used to extinguish kitchen fires (type K fires in the U.S.; type F in Europe), but may also be used on common combustible fires (type A).

CO2, oxygen, and nitrogen are what we breathe as air. Fires require oxygen as fuel, so fires may be smothered by removing the oxygen: this is how CO2 fire suppression works. A risk associated with CO2 is it is odorless and colorless, and our bodies will breathe it as air. By the time we begin suffocating due to lack of oxygen, it is often too late.

Halon extinguishes fire via a chemical reaction that consumes energy and lowers the temperature of the fire.Halon has ozone-depleting properties. Due to this effect, the 1989 Montreal Protocol (formally called the “Montreal Protocol on Substances That Deplete the Ozone Layer”) banned production and consumption of new halon in developed countries by January 1, 1994.

Recommended replacements for halon include the following systems: • Argon • FE-13 • FM-200

CO2, halon, and halon substitutes such as FM-200 are considered gas-based systems. All gas systems should use a countdown timer (both visible and audible) before gas is released. This is primarily for safety reasons, to allow personnel evacuation before release. A secondary effect is to allow personnel to stop the release in case of false alarm.

Water is usually the recommended fire suppression agent. Water (in the absence of electricity) is the safest suppression agent for people.

Dry pipe systems also have closed sprinkler heads: the difference is the pipes are filled with compressed air. The water is held back by a valve that remains closed as long as sufficient air pressure remains in the pipes. As the dry pipe sprinkler heads open, the air pressure drops in each pipe, allowing the valve to open and send water to that head.

Dry pipes are often used in areas where water may freeze, such as parking garages.

Deluge systems are similar to dry pipes, except the sprinkler heads are open and larger than dry pipe heads. The pipes are empty at normal air pressure; the water is held back by a deluge valve.

(My) CISSP Notes – Cryptography

Note: This notes were made using the following books: “CISPP Study Guide” and “CISSP for dummies”.

Cryptographic concepts

Cryptology is the science of secure communications. Cryptography creates messages whose meaning is hidden; cryptanalysis is the science of breaking encrypted messages (recovering their meaning).

A cipher is a cryptographic algorithm. A plaintext is an unencrypted message.

Cryptography can provide confidentiality (secrets remain secret) and integrity (data is not altered in an unauthorized manner). Cryptography can also provide authentication (proving an identity claim). Additionally, cryptography can provide nonrepudiation, which is an assurance that a specific user performed a specific transaction and that the transaction did not change.

Diffusion means the order of the plaintext should be “diffused” (or dispersed) in the ciphertext. Confusion means that the relationship between the plaintext and ciphertext should be as confused (or random) as possible.

Cryptographic substitution replaces one character for another; this provides diffusion. Permutation (also called transposition) provides confusion by rearranging the characters of the plaintext, anagram-style.

The work factor describes how long it will take to break a cryptosystem (decrypt a ciphertext without the key).

A monoalphabetic cipher uses one alphabet: a specific letter (like “E”) is substituted for another (like “X”). A polyalphabetic cipher uses multiple alphabets: “E” may be substituted for “X” one round, and then “S” the next round.

There are three primary types of modern encryption: symmetric, asymmetric, and hashing.

one-time pad uses identical paired pads of random characters, with a set amount of characters per page.

The one-time pad is the only encryption method that is mathematically proven to be secure, if the following three conditions are met: the characters on the pad are truly random, the pads are kept secure, and no page is ever reused.

The first known use of a one-time pad was the Vernam Cipher, named after Gilbert Vernam, an employee of AT&T Bell Laboratories.

COCOM is the Coordinating Committee for Multilateral Export Controls, which was in effect from 1947 to 1994.

Symmetric encryption

Symmetric encryption uses one key to encrypt and decrypt.

Symmetric encryption may have stream and block modes. Stream mode means each bit is independently encrypted in a “stream.” Block mode ciphers encrypt blocks of data each round.

An initialization vector is used in some symmetric ciphers to ensure that the first encrypted block of data is random. This ensures that identical plaintexts encrypt to different ciphertexts.

Chaining (called feedback in stream modes) seeds the previous encrypted block into the next block to be encrypted.

Symmetric encryption advantages: speed, strength (strength is gained when used with large keys, 128 bits, 256 bits or larger), availability (there are many algorithms available to select and use).

Symmetric encryption disadvantages: keys distribution (secure distribution of the keys is absolutely required), scalability (a different key is required for each pair of communication parties), limited functionality (symmetry systems can’t provide authentication or non-repudiation).

DES (Data Encryption Standard)

DES is a block cypher that uses a 64-bit block size (meaning it encrypts 64 bits each round) and a 56-bit key.

DES can use five different modes to encrypt data. The modes’ primary difference is block versus (emulated) stream, the use of initialization vectors, and whether errors in encryption will propagate to subsequent blocks.

The five modes of DES are:

  • Electronic Code Book (ECB) – is the simplest and weakest form of DES. It uses no initialization vector or chaining. Identical plaintexts with identical keys encrypt to identical ciphertexts.
  • Cipher Block Chaining (CBC) – is a block mode of DES that XORs the previous encrypted block of ciphertext to the next block of plaintext to be encrypted. The first encrypted block is an initialization vector that contains random data. This “chaining” destroys patterns. One limitation of CBC mode is that encryption errors will propagate: an encryption error in one block will cascade through subsequent blocks due to the chaining, destroying their integrity.
  • Cipher Feedback (CFB) – is very similar to CBC; the primary difference is CFB is a stream mode.Errors will not propagate.
  • Output Feedback (OFB) – is also a stream cipher very similar to CFB. In this mode, previous plaintext is used as feedback (chaining) for key generation.
  • Counter Mode (CTR) This mode shares the same advantages as OFB (patterns are destroyed and errors do not propagate) with an additional advantage: since the feedback can be as simple as an ascending number, CTR mode encryption can be done in parallel.

Triple DES

Triple DES applies single DES encryption three times per block.

Triple DES has held up well after years of cryptanalysis; the primary weakness is that it is slow and complex compared to newer symmetric algorithms such as AES or Twofish.

Triple DES applies DES encryption three times per block. FIPS 46-3 describes Encrypt, Decrypt, Encrypt” (EDE) order using three keying options: one, two, or three unique keys (called 1TDES EDE, 2TDES EDE, and 3TDES EDE, respectively).

If you “decrypt” with a different key than the one used to encrypt, you are really encrypting further. Also, EDE with one key allows backwards compatibility with single DES.

2TDES EDE uses key 1 to encrypt, key 2 to “decrypt,” and key 1 to encrypt. This results in 112 bits of key length.

3TDES EDE (three different keys) is the strongest form, with 168 bits of key length.

International Data Encryption Algorithm

The International Data Encryption Algorithm is a symmetric block cipher designed as an international replacement to DES. The IDEA algorithm is patented in many countries. It uses a 128-bit key and 64-bit block size.

Advanced Encryption Standards (AES)

AES was designed to replace DES. Two- and three-key TDES EDE remain a FIPS-approved standard until 2030, to allow transition to AES. Single DES is not a current standard, and not recommended.

AES has four functions:

  • SubBytes –  provides confusion by substituting the bytes of the State. The bytes are substituted according to a substitution table (also called an S-Box).
  • ShiftRows –  provides diffusion by shifting rows of the State.
  • MixColumns – provides diffusion by “mixing” the columns of the State via finite field mathematics,
  • AddRoundKey –  is the final function applied in each round. It XORS the State with the subkey. The subkey is derived from the key, and is different for each round of.

Blowfish and Twofish are symmetric block ciphers created by teams lead by Bruce Schneier,

RC5 and RC6 are symmetric block ciphers by RSA Laboratories.

RC6 was an AES finalist. It is based on RC5, altered to meet the AES requirements.

Asymmetric encryption

Asymmetric encryption uses two keys: if you encrypt with one key, you may decrypt with the other.

The main disadvantage of asymmetric encryption is theirs lower speed.

The main significant advantages of the asymmetric encryptions are extended functionality (can provide both confidentiality and authentication) and scalability (it solves the key management issues associated with symmetric keys systems).

Some mathematical concepts

The asymmetric algorithms uses “one-way functions”. An example of one-way function is factoring a composite number into its primes. Multiplying the prime number 6269 by the prime number 7883 results in the composite number 49 418 527. That “way” it’s easy to compute. Answering the question “which prime number times which prime number equals 49,418,527” is much more difficult. That problem is called factoring, This is the basis of RSA algorithm.

Factoring a large composite number (one thousands of bits long) is so difficult that the composite number can be safely publicly posted (this is the public key).

The primes that are multiplied to create the public key must be kept private (they are the private key).

A logarithm is the opposite of exponentiation. Computing 7 to the 13th power (exponentiation) is easy on a modern calculator: 96,889,010,407. Asking the question “96,889,010,407 is 7 to what power” (finding the logarithm) is more difficult. This is the basis of the Diffie-Hellman algorithm.

Key agreement allows two parties to securely agree on a symmetric key via a public channel, such as the Internet, with no prior key exchange.

Asymmetric and symmetric encryption are typically used together: use an asymmetric algorithm such as RSA to securely send someone an AES (symmetric) key. The symmetric key is called the session key; a new session key may be retransmitted periodically via RSA.

Use the slower and weaker asymmetric system for the one part that symmetric encryption cannot do: securely preshare keys. Once shared, leverage the fast and strong symmetric encryption to encrypt all further traffic.

Hash functions

Hash functions are primarily used to provide integrity: if the hash of a plaintext changes, the plaintext itself has changed.

MD5 creates a 128-bit hash value based on any input length.

MD6 is the newest version of the MD family.

SHA-1 creates a 160-bit hash value.

SHA-2 includes SHA-224, SHA-256, SHA-384, and SHA-512, named after the length of the message digest each creates.

HAVAL uses some of the design principles behind the MD family of hash algorithms, and is faster than MD5.

Cryptographic attacks

Cryptographic attacks are used by cryptanalysts to recover the plaintext without the  key.

  • brute-force attack  – generates the entire keyspace, which is every possible key.
  • known plaintext –  relies on recovering and analyzing a matching plaintext and ciphertext pair: the goal is to derive the key which was used.
  • chosen plaintext and adaptive chosen plaintext– a cryptanalyst chooses the plaintext to be encrypted in a chosen plaintext attack; the goal is to derive the key. Adaptive chosen plaintext begins with a chosen plaintext attack in round 1. The cryptanalyst then “adapts” further rounds of encryption based on the previous round.
  • chosen cipher text and adaptive chosen cipher text -chosen cipher text attacks mirror chosen plaintext attacks: the difference is that the cryptanalyst chooses the cipher text to be decrypted. This attack is usually launched against asymmetric crypto-systems, where the cryptanalyst may choose public documents to decrypt which are signed (encrypted) with a user’s public key.
  • meet-in-the-middle attack – encrypts on one side, decrypts on the other side, and meets in the middle.
  • known key attack – the term “known key attack” is misleading: if the cryptanalyst knows the key, the attack is over. Known key means the cryptanalyst knows something about the key, to reduce the efforts used to attack it. If the cryptanalyst knows that the key is an uppercase letter and a number only, other characters may be omitted in the attack.
  • differential cryptanalysis  – seeks to find the “difference” between related plaintexts that are encrypted.
  • linear cryptanalysis – is a known plaintext attack where the cryptanalyst finds large amounts of plaintext/ciphertext pairs created with the same key.
  • side-channel attacks – use physical data to break a cryptosystem, such as monitoring CPU cycles or power consumption used while encrypting or decrypting.
  • the birthday attack – is used to create hash collisions. Just as matching your birthday is difficult, finding a specific input with a hash that collides with another input is difficult. However, just like matching any birthday is easier, finding any input that creates a colliding hash with any other input is easier due to the birthday attack.
  • key clustering – occurs when two symmetric keys applied to the same plaintext produce the same ciphertext. This allows two different keys to decrypt the ciphertext.