(My) OWASP BeNeLux Days 2017 Notes – Training Day

These are my notes from the OWASP BeneLux Days 2017 on “Secure Development: Models and best practices” by Bart De Win.

The goal of the training was about how to improve the structure of an organization in order to enhance the security of (IT) applications.

The talk was around the following topics:

  • Software assurance maturity models
  • Introduction to SAMM and hands-on exercise/s
  • Secure Development in agile development
  • Tip and tricks for practical SDLC
  • Sneak preview of SAMM 2.0

Software assurance maturity models

Today we build more and more complex software:

  • multi platform;
  • mobile version; cloud
  • same application using different technological stacks

75% of vulnerabilities are application related

The state of the Secure Development LifeCycle (SDLC) today:

  • on focus on bugs not an (architectural) flows
  • (very often) do pen test just before going in live

The goal of  the SDLC is to develop and maintain software in a consisted and efficient way with  standards-compliance security quality.

SDLC Cornerstones:

  • peoples
  • process
    • activities
    • control gates
    • deliverables
  • knowledge
    • standards&guidelines
    • compliance
  • tools&component
    • development support
    • assessment tools
    • management tools

Introduction to SAMM and hands-on exercise

SAMM is an open framework to help organizations formulate and implement a strategy for software security that is tailored to the specific risks faced by an organization.

Other standards/frameworks that are in the same space as SAMM:

SAMM consists in 4 business functions each one containing 3 security practices. Each security practice have 4 maturity levels (from 0 to 3):

Each (SAMM) maturity level defines the following attributes:

  • objectives
  • activities
  • results
  • success metrics
  • cost
  • personnel
  • related levels

How do we start with SAMM: It is possible to start with the SAMM Toolbox Excel file in order to do an initial assessment for each of the  security processes (the Excel file will compute the maturity level). This initial assessment will help you to plan the improvements.

Secure Development in agile development

There are a mismatch between the agile development goal/s and the security goal/s

agile dev security
  • speed and flexibility
  • short cycles
  • limited documentation
  • functionality driven
  • stable and rigorous
  • extra activities
  • extensive analysis
  • non functional

Introducing security into agile development is not easy task and especially there is not a standardized way of doing it.

Some ideas and hints:

  • make security a natural part of the process
  • capture security requirements, policies and regulations in user stories

Sneak preview of SAMM 2.0

  • planned for end of next year.
  • model revision
  • more metrics
  • application to agile
  • benchmarking

5 (software) security books that every (software) developer should read

I must admit that the title is a little bit catchy; a better title would have been “5 software security books that every developer should be aware of“. Depending on your interest you might want to read entirely these books or you could just know that they exists. There must be tons of software security books on the market but this is my short list of books about software security that I think that each developer that is interested in software security should be aware of.

Hacking – the art of exploitation This book explains the basics of different hacking techniques, especially the non-web hacking techniques: how to find vulnerabilities (and defend against)  like buffer overflow or stack-based buffer overflow , how to write shellcodes, some basic concepts on cryptography and attacks linked to the cryptography like the man-in-the-middle attack of an SSL connection. The author tried to make the text easy for non-technical peoples but some programming experience is required (ideally C/C++) in order to get the best of this book. You can see my full review of the book here.

Iron-Clad Java: Building secure web applications This book presents the hacking techniques and the countermeasures for the web applications; you can see this books as complementary of the previous one; the first one contains the non-web hacking techniques, this one contains (only) web hacking techniques; XSS, CSRF, how to protect data at rest, SQL injection and other types of injections attacks. In order to get the most of the book some Java knowledge is required. You can see my full review of the book here.

Software Security-Building security in  This books explains how to introduce the security into the SDLC; how to introduce abuse cases and security requirements in the requirements phase, how to introduce risk analysis (also known as Threat Modeling) in the design phase and software qualification phase. I really think that each software developer should at least read the first chapter of the book where the authors explains why the old way of securing application (seeing the software applications as “black boxes” than can be protected using firewalls and IDS/IPS) it cannot work anymore in the today software landscape. You can see my full review of the book here: Part 1, Part 2 and Part 3.

The Tangled Web: A Guide to Securing Modern Web Applications This is another technical book about security on which you will not see a single line of code (the Software Security-Building security in is another one) but it highly instructive especially if you are a web developer. The book presents all the “bricks” of the today Internet: HTTP, WWW, HTML, Cookies, Scripting languages, how these bricks are implemented in different browsers and especially how the browsers are implementing the security mechanism against rogue applications. You can see my full review of the book here.

Threat modeling – designing for security Threat modeling techniques (also known as Architectural Risk Analysis) were around for some time but what it has changed in the last years is the accessibility of these technique for the software developers.  This book is one of the reasons for which the threat modeling is accessible to the developers. The book is very dense but it  suppose that you have no knowledge about the subject. If you are interested in the threat modeling topic you can check this ticket: threat modeling for mere mortals.

Book review: Iron-Clad Java Building Secure Web Applications

This a review of the Iron-Clad Java: Building Secure Web Applications book.

(My) Conclusion

I will start with the conclusion because it’s maybe the most important part of this review.

For me this is a must read book if you want to write more robust (web and non web) applications in Java, it covers a very large panel of topics from the basics of securing a web application using HTTP/S response headers to handling the encryption of sensitive informations in the right way.

Chapter 1: Web Application Security BasicsironCladJavaBook

This chapter is an introduction to the security of web application and it can be split in 2 different types of items.

The first type of items is what I would call “low-hanging fruits” or how you could improve the security  of your application with a very small effort:

  • The use of HTTP/S POST request method is advised over the use of HTTP/S GET. In the case of POST the parameters are embedded in the request body, so the parameters are not stored and visible in the browser history and if used over HTTPS are opaques to a possible attacker.
  • The use of the HTTP/S response headers:
    • Cache-Control – directive that instructs the browser how should cache the data.
    • Strict-Transport-Security – response header that force the browser to alway use the HTTPS protocol. This it can protect against protocol downgrade attacks and cookie hijacking.
    • X-Frame-Options – response header that can be used to indicate whether or not a browser should be allowed to render a page in a <frame>, <iframe> or <object> . Sites can use this to avoid clickjacking attacks, by ensuring that their content is not embedded into other sites.
    • X-XSS-Protection – response header that can help stop some XSS atacks (this is implemented and recognized only by Microsoft IE products).

 The second types of items are more complex topics like the input validation and security controls. For this items the authors just scratch the surface because all of this items will be treated in more details in the future chapters of the book.

Chapter 2: Authentication and Session Management

This chapter is about how a secure authentication feature should work; under the authentication topic is included the login process, session management, password storage and the identity federation.

The first part is presenting the general workflow of login and session management (see next picture) and for every step of the workflow  some dos and don’t are described.

login and session management workflow

login and session management workflow

The second part of the chapter is about common attacks on the authentication and for each kind of attack a solution to mitigated is also presented. This part of the chapter is strongly inspired from the OWASP Session Management Cheat Sheet which is rather normal because one of the authors (Jim Manico) is the project manager of the OWASP Cheat Sheet Series.

If you want to have a quick view of this chapter you can take a look to the presentation Authentication and Session Management done by Jim.

Even if you are not implementing an authentication framework for you application, you could still find good advices that can be applied to other web applications; like the use of the use of the secured and http-only attributes for cookies and the increase of the session ID length.

Chapter 3: Access Control

The chapter is about the advantages and pitfalls of implementing an authorization framework and can be split in three parts.

The first part describes the goal of an authorization framework and defines some core terms:

  • subject : the service making the request
  • subject attributes : the attributes that defines the service making the request.
  • group : basic organizational structure
  • role : a functional abstraction that uniquely describe system collaborators with similar or unique duties.
  • object : data being operating on.
  • object attributes : the attributes that defines the type of object being operating on.
  • access control rules : decision that need to be made to determine if a subject is allowed to access an object.
  • policy enforcement point : the place in code where the access control check is made.
  • policy decision point : the engine that takes the subject, subject attributes, object, object attributes and evaluates them to make an access control decision.
  • policy administration point : administrative entry in the access control system.

The second part of the chapter describes some access control (positive) patterns and anti-patterns.

Some of the (positive) access control patterns: have a centralized policy enforcement point  and policy decision point (not spread through the entire code),  all the authorization decisions should be taken on server-side only (never trust the client), the changes in the access control rules should be done dynamically (should not be necessary to recompile or restart/redeploy the application).

For the anti-patterns, some of then are just opposite of the (positive) patterns : hard-coded policy (opposite of “changes in the access control rules should be done dynamically”), adding the access control manually to every endpoint (opposite of have a centralized policy enforcement point  and policy decision point)

Others anti-patterns are around the idea of never trusting the client: do not use request data to make access control policy decisions and fail open (the control access framework should cope with wrong or missing parameters coming from the client).

The third part of the chapter is about different approaches (actually two) to implement an access control framework. The most used approach is RBAC (Role Based Access Control) and is implemented by some well knows Java access control frameworks like Apache Shiro and Spring Security. The most important limitation of RBAC is the difficulty of implementing data-specific/contextual access control. The use of ABAC (Attribute Based Access Control) paradigm can solve the data-specific/contextual access control but there are no mature frameworks on the market implementing this.

Chapter 4: Cross-Site Scripting Defense

This chapter is about the most common vulnerability found across the web and have two parts; the presentation of different types of cross-site scripting (XSS) and the way to defend against it.

XSS is a type of attack that consists in including untrusted data into the victim (web) browser. There are three types of XSS:

  • reflected XSS (non persistent) – the attacker tampers the HTTP request to submit malicious JavaScript code. Reflected attacks are delivered to victims via e-mail messages, or on some other web site. When a user clicks on a malicious link, submitting a specially crafted form the injected code travels to the vulnerable web site, which reflects the attack back to the user’s browser. The browser then executes the code because it came from a “trusted” server.
  • stored XSS (persistent XSS) – the malicious script is stored on the server hosting the vulnerable web application (usually in the database) and it is served later to other users of the web application when the users are loading the vulnerable page. In this case the victim does not require to take any attacker-initiated action.
  • DOM-based XSS – the attack payload is executed as a result of modifying the DOM “environment” in the victim’s browser.

For the defense techniques the big picture is that the input validation and output encoding should fix (almost) all the problems but very often various factors needs to be considered when deciding the defense technique.

Some projects are presented for the input validation (OWASP Java Encoder Project) and output encoding (OWASP HTML Sanitizer, OWSP AntiSamy).

Chapter 5: Cross-Site Request Forgery Defense and Clickjacking

Chapter 6: Protecting Sensitive Data

This chapter is articulated around three topics; how to protect (sensitive) data in transit, how to protect (sensitive) data at rest and the generation of secure random numbers.

How to protect the data in transit

The standard way to protect data in transit is by use of cryptographic protocol Transport Layer Security (TLS). In the case of web applications all the low level details are handled by the web server/application server and by the client browser but if you need a secure communications channel programmatically you can use the Java Secure Sockets Extension (JSSE). The authors recommendations for the cipher suites is to use the JSSE defaults.

Another topic treated by the authors is about the certificate and key management in Java. The notions of trustore and keystore are very well explained and examples about how to use the keytool tool are provided. Last but not least examples about how to manipulate the trustores and keystores programmatically are also provided.

How to protect data at rest

The goal is how to securely store the data but in a reversible way, so the data must be wrapped in protection when is stored and the protection must be unwrapped later when it is used.

For this kind of scenarios, the authors are focusing on Keyczar which is a (open source) framework created by Google Security Team having as goal to make it easier and safer the use cryptography for the developers. The developers should not be able to inadvertently expose key material, use weak key lengths or deprecated algorithms, or improperly use cryptographic modes.

Examples are provided about how to use Keyczar for encryption (symmetric and asymmetric) and for signing purposes.

 Generation of secure random numbers

Last topic of the chapter is about the Java support for the generation of secure random numbers like the optimal way of using the java.security.SecureRandom (knowing that the implementation depends on the underlying platform) and the new cryptographic features of Java8 (enhance of the revocation certificate checking, TLS Server name indication extension).

Chapter 7: SQL Injection and other injection attacks

This chapter is dedicated to the injections attacks; the sql injection being treated in more details that the other types of injection.

SQL injection

The sql injection mechanism and the usual defenses are very well explained. What is interesting is that the authors are proposing solutions to limit the impact of SQL injections when the “classical” solution of query parametrization cannot be applied (in the case of legacy applications for example): the use of input validation, the use of database permissions and the verification of the number of results.

Other types of injections

XML injection, JSON-Based injection and command injection are very briefly presented and the main takeaways are the following ones:

  • use a safe parser (like JSON.parse) when parsing untrusted JSON
  • when received untrusted XML, an XML schema should be applied to ensure proper XML structure.
  • when XML query language (XPath) is intermixed with untrusted data, query parametrization or encoding is necessary.

Chapter 8: Safe File Upload and File I/O

The chapter speaks about how to safety treat files coming from external sources and to protect against attacks like file path injection, null byte injection, quota overloaded Dos.

The main takeaways are the following ones: validate the filenames (reject filenames containing dangerous characters like “/” or “\”), setting a per-user upload quota, save the file to a non-accessible directory, create a filename reference map to link the actual file name to a machine generated name and use this generated file name.

Chapter 9: Logging, Error Handling and Intrusion Detection

Logging

What should be be logged: what happened, who did it, when it happened, what data have been modified, and what should not be logged: sensitive information like sessions IDs, personal informations.

Some logging frameworks for security are presented like OWASP ESAPI Logging and Logback. If you are interested in more details about the security logging you can check OWASP Logging Cheat Sheet.

Error Handling

On the error handling the main idea is to not leak to the external world stacktraces that could give valuable information about your application/infrastructure to an attacker. It is possible to prevent this by registering to the application level static pages for each type of error code or by exception type.

Intrusion Detection

The last part of the chapter is about techniques to help monitor end detect  and defend against different types of attacks. Besides the “craft yourself” solutions, the authors also re presenting the OWASP AppSensor application.

Chapter 10: Secure Software Development Lifecycle

The last chapter is about the SSDLC (Secure Software Development Life Cycle) and how the security could be included in each steps of development cycle. For me this chapter is not the best one but if you are interested about this topic I highly recommend the Software Security: Building Security in book (you can read my own review of the book here, here and here).

OWASP Security Knowledge Framework – the missing tutorial

skf-miniA few months  ago (during BeneLux OWASP Days 2016) I’ve seen a presentation of the OWASP Security Knowledge Framework. I found the presentation very interesting so I decided to dig a little bit to learn more about OWASP Security Knowledge Framework a.k.a SKF. I found the official documentation a little bit sparse so after playing with SKF a few days I decided to write on paper what I have learned.

Introduction

SKF is a tools that helps the software developers to ease the integration of security into SDLC (Software Development Lifecycle). For the end-user, SKF can be used as web application which can be accessed after creating an account.

SKF web site have deployed a demo application, that can be accessed here SKF demo site (the username is admin and the password is test-skf. (be aware that the site content is scratched every hour).

Installation

If you want to install SKF in-house, then you can follow the installation instructions (installation instructions under Ubuntu, MacOS and Windows are provided and also Chef and AWS). Another installation option would be to use Docker; in this case you could use the following Docker image that I created. (the image is based on Ubuntu 14.04 64 bits version).

Once the application is running (in the case of Ubuntu manual installation it will run over HTTPS on port 5443) you have to unlock the default admin account (I will speak later about user and group management in SKF). This procedure is described in First run page; what is important to note is that on the “first login” page you must use the pincode 1234 and the email [email protected] (these values are hard-coded).

SKF Big picture

The SKF is articulated around 4 security topics:

  • (security) knowledge base.
  • (security) code examples.
  • introduction of the security checklists for applications using the OWASP Application Security Verification Standard (ASVS) project.
  • introduction of the security requirements in the SDLC.

The knowledge base

The SKF knowledge base contains the descriptions and the solutions to over 200 vulnerabilities, attacks and security best practices: API responses security headers, Access Control patterns, Command injection and many, many more.

The code examples

SKF also contains a few dozens of code examples of best practices to write secure code; the examples are written in PHP and C# languages.

Security Checklists

SKF offers also the possibility to create projects and users, the idea being that the users can be part of one or more projects and each project can contains a list of security checklists and security requirements.

The admin user (the user that have been  unlocked after the installation) can create projects and users. For the user creation, a unique pincode is generated and the new user need to use this pincode the first time when he connects to the application.

The security checklists are representing a way to testing web application technical security controls and also provides developers with a list of requirements for secure development. SKF uses the OWASP Application Security Verification Standard (ASVS) checklists. SKF shows the checklists in a very user friendly way and the checklists can be customized in case your project have special security requirements. It is possible to add as many checklists as wanted end every checklists can be downloaded as a .docx document.

The OWASP ASVS contains the following verification criteria:

  • Architecture, design ant threat modeling.
  • Authentication.
  • Session management.
  • Access control.
  • Malicious input handling.
  • Cryptography at rest.
  • Error handling and logging.
  • Data protection.
  • Communications.
  • HTTP security configuration.
  • Malicious controls.
  • Business logic.
  • Files and resources.
  • Mobile
  • Web services
  • Configuration

Security requirements

For me, the most interesting feature of the SFK is the ability to create and attach to each project multiple items called functions. The basic idea is that the user can choose from a list of security requirements depending of the feature that should be implemented; for example you if for implementing a new feature, an eternal library will be used then you can add as security requirement the “third party software” function.  Each security requirement contains a description and a solution about how to be handled.

The OWASP SKF contains the following security requirements:

  1. third party software
  2. sub-domains
  3. Access controls or Login systems
  4. User registration
  5. Form
  6. Sessions
  7. Password forget functions
  8. Forward or redirect
  9. GET variables or parameters
  10. XML files
  11. File Download
  12. File upload
  13. Regular expressions
  14. Eval type functions
  15. Private user data
  16. System commands
  17.  SSI commands
  18. XSLT input and output
  19. HTTP headers
  20. LDAP commands
  21. User-input in HTML output
  22. X-Path
  23. File inclusion
  24. Path or Filename
  25. SQL commands

(My) Conclusion

What I like about OWASP SKF is that it tries to introduce the secure coding practices into the SDLC in a easy and customizable way; ideally you should use all the features of the SKF but it’s up to each team/project to choose how  SKF could help to have a more secure code.

On the negative side  I would have the following remarks:

  • the application looks unstable; very often I have “Internal server error” on my Docker instance.
  • the code examples for Java are in the “Coming Soon” status for the last (at least) 8 months; maybe should be removed to not set-up unreasonable expectations.
  • I (personally) do not appreciate the ergonomy of the user interface; the actions linked projects (project creation, results) are mixed with the user management actions (user and group creation) and with other actions which are independent of projects and groups (code examples and knowledge base).  As a new user I was very confused and I didn’t understood right away that the 4 SKF features can be used independently.