CSSLP – Adventures in the programming jungle

(My) CSSLP Notes – Software acceptance

1 November, 201719 May, 2017Adrian Citu

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

Software acceptance is the life cycle process of officially or formally accepting new or modified software components, which when integrated form the information system.

Pre-Release activities:

completion criteria – are all the functional and security requirements completed as expected.
change management – is there a process in place to handle change requests.
approval to deploy/release – have all of the required authorities sign off.
risk acceptance and exception policy – is the residual risk acceptable or tracked as an exception.
documentation – are all the necessary documentation in place.

Post-Release activities:

validation & verification (V&V) – Validation means that the software meets the specified user requirements. Verification describes proper software construction. V&V is not an ad hoc process but it is a very structured and systematic approach to evaluate the software technical functionality. The evaluation can be divided in two main activities:
- reviews
  - design (review).
  - code (review).
- testing
  - error detection (tests).
  - acceptance (tests).
  - independent third party (tests).
certification and accreditation – Certification is the technical verification of the software functional and assurance level. Accreditation is management’s formal acceptance of the system after an understanding of the risks to that system.

(My) CSSLP Notes – Secure Software Testing

2 October, 201719 May, 2017Adrian Citu

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

Security Quality Assurance Testing

Standards for Software Quality Assurance

ISO 9216 – provides guidance for establishing quality in software products.
ISO 21827 SSE-CMM (Systems Security Engineering Capability Maturity Model) – addresses security engineering activities that span the entire secure system lifecycle.
OSSTMM (Open Source Security Testing Methodology Manual) – provides a scientific methodology for assessing operational security built upon analytical metrics.

Types of software QA Testing

functional testing – Software testing is performed to primarily attest the functionality of the software as expected by the business or customer.
unit testing
system/integration testing – assures that the overall system is compliant with the system-level requirements.
regression testing – performed to validate that the software did not break previous functionality or security and regress to a non-functional or insecure state.
non-functional testing – covers testing for the recoverability and environmental aspects of the software.
performance testing
- load testing – process of subjecting the software to volumes of operating tasks or users until it cannot handle any more, with the goal of identifying the maximum operating capacity for the software
- stress testing – aimed to determine the breaking point of the software, i.e., the point at which the software can no longer function.
user acceptance testing (smoke testing) – UAT is generally performed as a black box test which focuses primarily on the functionality and usability of the application.

Security testing methods

white-box testing – testing is performed on a system with the full knowledge of the working components including the source code and its operations.
black-box testing – the attacker has no knowledge of the inner workings of the software under test.

Type of security testing

scanning – automatic enumerations of specific characteristics of an application or network
cryptographic validation testing –
penetration testing – the main objective of penetration testing is
to see if the network and software assets can be compromised by exploiting the vulnerabilities that were determined by the scans.
fuzzing – brute-force method of addressing input validation issues and vulnerabilities.
simulation testing – testing the application in an environment that mirrors the associated production environment.

(My) CSSLP Notes – Secure Software Implementation

1 September, 201719 May, 2017Adrian Citu

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

Common Software Vulnerabilities and Controls

Some well-known and useful examples of vulnerability databases and

tracking systems:

National Vulnerability Database (NVD) -U.S. government repository of vulnerabilities and vulnerability management data.
US Computer Emergency Response Team (CERT) Vulnerability Notes Database – The CERT vulnerability analysis project aims at reducing security risks due to software vulnerabilities in both developed and deployed software.
Open Source Vulnerability Database – An independent and open source database that is created by and for the security community.
OWASP Top 10 – The OWASP Top 10 List, in addition to considering

the most common application security issues from a weaknesses or

vulnerabilities perspective, views application security issues from an

organizational risks.
Common Weakness Enumeration (CWE) – Provides a common language for describing architectural, design or coding software security weaknesses.
Common Vulnerabilities and Exposures (CVE) – A dictionary of publicly known information security vulnerabilities and exposures. It is free for use and international in scope.

The most common software security vulnerabilities and risks

buffer overflow – is the condition that occurs when data that is being copied into the buffer (contiguous allocated storage space in memory) is more than what the buffer can handle.
- stack overflow – buffer has been overflowed in the stack space.
  the data flows from one buffer space into another, causing the return address instruction pointer to be overwritten.
- heap overflow – a heap overflows does not necessarily overflow but corrupts the heap memory space (buffer), overwriting variables and function pointers on the heap.
injection flows – occur when the user supplied data is not validated before being processed by an interpreter.
- SQL injection
- OS Command injection
- LDAP injection
- XML injection – software does not properly filter or quote special characters or reserved words that are used in XML, allowing an attacker to modify the syntax, contents or commands before execution.
cross-site scripting – A web application is said to be susceptible to XSS vulnerability when the user supplied input is sent back to the browser client without being properly validated and its content escaped.
- Non-persistent (Reflected) – the user supplied input script that is injected (also referred to as payload) is not stored but merely included in the response from the web server, either in the results of a search or an error message.
- Persistent (Stored) – the injected script is permanently stored on the target servers, either in a database, a message forum, a visitor log or an input field. Each time the victims visit the page that has the injected code stored in it or served to it from the web server, the payload script executes in the user’s browse
- DOM based – the payload is executed in the victim’sbrowser as a result of DOM environment modifications on the client side. The HTTP response (or the web page) itself is not modified, but weaknesses in the client side allows the code contained in the web page client to be modified, so that the payload can be executed.
insecure direct object references – an unauthorized user or process can invoke the internal functionality of the software by manipulating parameters and other object values that directly reference this functionality.
security misconfiguration -Some of the common examples of security misconfigurations:
- Missing software and operating system patches.
- Lack of perimeter and host defensive controls such as firewalls,
  filters.
- Installation of software with default accounts and settings.
- Installation of the administrative console with default configuration settings.
social engineering
- Phishing
- Pharming – scamming practice in which malicious code is installed on a system or server which misdirects users to fraudulent web sites without the user’s knowledge or consent.
- Vishing – made up of two words, “voice” and “phishing” and is the criminal fraudulent activity in which an attacker steals sensitive information using deceptive social engineering techniques on VoIP networks.
- SMSishing

Defensive Coding Practices

input validation – use blacklist or whitelist technique.
canonicalization (C14N) -process of converting data that has more than one possible representation to conform to a standard canonical form.
sanitization -process of converting something that is considered dangerous into its innocuous form. Both inputs and outputs can be sanitized.
- stripping – removing harmful characters from user supplied input.
- substitution – replacing user supplied input with safer alternatives.
- literalization – using properties that render the user supplied input to be treated as a literal form.
error handling – error messages must be non-verbose and explicitly specified in the software. Redirect errors and exceptions to a custom and default error handling location.
cryptographic agility – ability to manage the specifics of the cryptographic functions that are embedded in code without recompiling, typically through a configuration file.
tokenization – process of replacing sensitive data with unique
identification symbols that still retain the needed information about the data, without compromising its security.
anti-tampering – techniques assure integrity assurance and protection against unauthorized and malicious alterations of the software code and/or the data.
- obfuscation.
- code-signing.

Secure Software Processes

In addition to writing secure code, there are certain processes that must be conducted during the implementation phase that can assure the security of the software:

versioning
code analysis
- static
- dynamic
code/peer review

(My) CSSLP Notes – Secure Software Design

1 August, 201719 May, 2017Adrian Citu

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

Design Process

Attack Surface Evaluation

A software or application’s attack surface is the measure of its exposure of

being exploited by a threat agent i.e., weaknesses in its entry and exit points that a malicious attacker can exploit to his or her advantage.

The attack surface evaluation attempts to enumerate the list of features that

an attacker will try to exploit.

Threat Modeling

Threat modeling is the process used to identify and document all the threats to system.

The threat modeling process have 3 phases:

model the system for which you want to find the threats.
find the threats.
1. STRIDE model.
2. attack trees – An attack tree is a hierarchical tree-like structure, which has either an attacker’s objective (e.g., gain administrative level privilege, determine application makeup and configuration, bypass authentication mechanisms, etc.) or a type of attack
  (e.g., buffer overflow, cross site scripting, etc.) at its root node.
address each threat found in the previous step. Once identified,each threat must be evaluated according to the risk attached to it. There are several ways to quantitatively or qualitatively determine the risk ranking for a threat. These range from the simple, non-scientific, Delphi heuristic methodology to more statistically sound risk ranking using the probability of impact and the business impact.
document and validate.

More details about threat modeling can be found here : Threat Modeling for mere mortals and (My) OWASP BeNeLux Days 2016 Notes – Training Day.

Design Considerations

This part is linked to the Secure Software Concepts and contains how the security software concepts can be applied to have a secured application.

confidentiality – use cryptographic and masking techniques
integrity – use hashing (or hash functions), referential integrity design (uses primary keys and related foreign keys in the database to assure data integrity), resource locking (when two concurrent operations are not allowed on the same object (say a record in the database), because one of the operations locks that record from allowing any changes to it, until it completes its operation, it is referred to as resource locking), and code signing.
availability – replication, fail-over and scalability techniques can be used to design the software for availability.
authentication – use multi-factor authentication and single sign on (SSO). Rely of already existing mechanism if possible (like the ones offered by the operating system).
authorization – rely of already existing mechanism if possible.
accounting (audit) – determine of what elements should be logged and under what circumstances.

Some of the common, insecure design issues observed in software are the

following:

improper implementation of least privilege
software fails insecurely
authentication mechanisms are easily bypassed
security through obscurity
improper error handling
weak input validation

Architecture system with secured design principles:

good enough security – care should be taken to ensure that the security elements are in response with the actual risk associated with the potential vulnerability; do not over-engineer.
least privilege – use of accounts with non-administrative abilities.
Modular programming is a software design technique in which the entire program is broken down into smaller sub-units or modules. Each module is discrete with unitary functionality and is said to be therefore cohesive, meaning each module is designed to perform one and only one logical operation.
separation of duties – the programmer should not be allowed to review his own code nor should a programmer have access to deploy code to the production environment.
defense in depth
- use of input validation along with prepared statements or stored
  
  procedures, disallowing dynamic query constructions using user
  
  input to defend against injection attacks.
- disallowing active scripting in conjunction with output encoding
  
  and input- or request-validation to defend against Cross-Site
  
  Scripting (XSS).
fail safe
- the user is denied access by default and the account is locked out after the maximum number (clipping level) of access attempts is tried.
- errors and exceptions are explicitly handled and the error messages are non-verbose in nature.
- not designing the software to ignore the error and resume next
  
  operation
economy of mechanism – trade-off that happens between the
usability of the software and the security features that need to be designed and built in.
- Unnecessary functionality or unneeded security mechanisms should be avoided.
- Strive for simplicity.
- Strive for operational ease of use.
complete mediation –
open design – the inverse of the open design principle is security through obscurity, which means that the software employs protection mechanisms whose strength is dependent on the obscurity of the design.
least common mechanism – mechanisms common to more than one user or process are designed not to be shared. Design should compartmentalize or isolate the code (functions) by user roles, since this increases the security of the software by limiting the exposure.
psychological acceptance – security principle that states that security mechanisms should be designed to maximize usage, adoption, and automatic application.The security protection mechanisms:
- are easy to use,
- do not affect accessibility.
- are transparent to the user.
weakest link – when designing software, careful attention must be
given so that there are no exploitable components.
leverage existing components – reusing tested and proven, existing libraries and common components has good security benefits.

Securing commonly used architectures

mainframe architecture
distributed architecture
- client/server
- p2p
service oriented architecture
- An ESB is a software architectural pattern that facilitates communication between mutually interacting software application.
- web-services
  - SOAP
  - REST
rich internet aplications (RIA)

Service models:

Infrastructure as a Service (IaaS) -infrastructural components such as networking equipment, storage, servers and virtual machines are provided as services and managed by the cloud service provider.
Platform as a Service (PaaS) -in addition to infrastructural components, platform components such as operating systems, middleware and runtime are also provided as services and managed by the cloud service provider.
Software as a Service (SaaS) – in addition to infrastructural and platform components, data hosting and software applications are provided as services and managed by the cloud service provider.

Digital Rights Management

The expression of rights is made possible by formal language, known as Rights Expression Language (REL). Some examples of REL include the following:

Open Digital Rights Language (ODRL) – A generalized, open standard under development that expresses rights using XML.
eXtensible rights Markup Language (XrML) – Another generalized REL that is more abstract than ODRL. XrML is more of a meta-language that can be used for developing other RELs.
Publishing Requirements for Industry Standard Metadata

(PRISM) – Unlike ODRL and XrML, PRISM can be used to express

rights specific to a task and is used for syndication of print media

content such as newspapers and magazine.

Trusted computing:

Trusted Platform Module (TPM) – specification used in personal computers and other systems to ensure protection against disclosure of sensitive or private information as well as the implementation of the specification itself.
Trusted Computing Base (TCB) – the set of all hardware, firmware and software components that are critical to its security.

(My) CSSLP Notes – Secure Software Requirements

3 July, 201719 May, 2017Adrian Citu

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

The 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.

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.

Requirements

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