OWASP Open Souce Review Project

Groups

Goals

• Experiencing the process of doing a code review, where you struggle with limited time, people, and knowledge - and too much code without good design documentation;
• Finding out about the capabilities and limitations of code analysis tools;
• Finding out how good current best practices for doing security code reviews are, in particular the OWASP ASVS, are;
• Getting some ideas of how (security) design, incl. the high level architecture and security design decisions, should be performed and documented to facilitate security reviews.

Whether you find all or indeed any security vulnerabilities is not so important, so resist the temptation of getting ideas from other groups. Indeed, we are hoping to use this experiment to get some empirical data on code reviews -- how many eyeballs make for secure code?

Practicalities

As a guide, the goal is that everyone spends around 50 hours in total for this project. You still have around 12 weeks, so spend a morning or afternoon a week.

The first time you get together with your group, fill in the questionnaire [odt] [doc] together and email it to Erik Poll.

What to do

Some things you may run into:

• The need for sampling? Some verification requirements may be too labour intensive to check exhaustively for the entire codebase. In such cases you might resort to sampling, i.e. only check the requirements in a few places, and then base your verdict on that sample. Different strategies are possible for this: you could choose a random sample (e.g. randomly pick some files of source code, or pick some part of the interface of the application to investigate in detail), or you could decide to focus on the most security-critical functionality parts of the code, or use a combination of these approaches.
• code vs configuration? At some places you may run into issues which depend not so much on the code but rather on the configuration of a particular installation of the code. The border between code and configuration is sometimes hard to draw; moreover, one can debate about how defensive code should be when it comes to facilitating/enforcing good and secure configuration. If you come across such issues, better to concentrate on the code first and not to get distracted into considering configuration issues. It is then good to document where you drew the line in doing the review. If you note that there are or may be important configuration issues that impact security, it is of course useful to flag these in your report.
• Finding one vs all security flaws? A single security flaw of a certain kind can already show that some verification condition is broken, so it is not essential to then go hunting for more flaws of the same type. Of course, if you do notice that some problem occurs multiple times, then it's good to record this.

What to report

A suggested organisation of the report would be in the sections as listed below, but feel free to diverge of this if you think makes sense. In the organisation below the section giving the verdict would be the longest, simply because it has to list all the ASVS security requirements. Describing the organisation or process for the review might only take half a page or so, and the reflection would probably be longer than that.

1. Organisation
   Briefly describe the way you organised the review.

   E.g. did you split the work by files in the code, or by category of security requirements? Did you double-check important findings? Or did you use several pairs of eyeballs on the same code/ security requirement, in the hope that more eyeballs spot more problems? (How) did you integrate using the static code analysis tools into this process? Did you use other tools and methods?
   Have you tried to run the application? (If so, was this useful, and did you find than running the application was helpful to then review the code, understanding its functionality better? But you might want to dicuss this in the Reflection section.)

2. Verdict
   Give your judgement for each of the verification requirements, with a short motivation.

   The judgement could be PASS or FAIL, but don't hesitate to say

   • DON'T KNOW, if you are unsure of whether the code meets the requirement, if you are unsure what the ASVS requirement means, or or if you did not have time to look at it.
   • NOT RELEVANT, if a given requirements does not apply, and therefore you don't need to look at it. (Or you could call that a PASS, for the trivial reason that it does not apply.)
   If need be, come up with other sensible judgments, besides PASS, FAIL, DON'T KNOW, etc.

   With respect to motivation: ideally you'd like to give a brief and concise justification, of say one short sentence, for your verdict of a verification requirement. But if a verification requirement is very clear and it is straightforward how one would check it, it might not be worthwhile to write up anything. Conversely, sometimes it may be quite hard to argue that some verification requirement is met: the violation of a requirement is often easier to motivate (namely with a counterexample) than the satisfaction.

   If you resorted to sampling to judge some requirement (or group of requirements) or if you considered some configuration aspects out of scope, that would be something to mention too. You could also say that in Section 1, if that makes more sense.

3. Reflection
   Reflect on the whole process, including
   • the ASVS,
   • the use of static code analysis tools,
   • the way you organised the process,
   • and possibly also the TestCMS code.
   For example, questions to consider are:
   • How good (useful, clear, ...) is the ASVS? How could it be improved?
   • How useful were code analysis tools? (Both the basic RATS/ITS4 and the more powerful Fortify tool.) How could they be improved? How did you experience the rates and amounts of false and true positives? How might that be improved?
   • What were the bottlenecks in doing the security review in your experience?
   • Maybe in the points above you can distinguish different (types of) security flaws or verification requirements. E.g., are some (categories of) verification requirements easier to check than others?
   • If you would have to do something like this again, what would you do differently? Eg. about organising things within the group: i.e., in retrospect, what do you think the best approach is to organise and divide the work in a team? (Dividing the verification requirements over the team members? Or by dividing the code? Or letting everyone look at everything, because different people will spot different things? Or work in pairs where one person confirms the findings of the other? ...)
   • About the TestCMS code: are there important aspects that could (or should) be changed to improve security? Or aspects that could be changed to facilitate doing a security reviews?
     This last question might be generalised, to (web) applications in general, rather than this specific example of the TestCMS: ie. if you were to develop an application that will need to be subjected to a security review, would you do anything differently, given your experience in doing this, and if so, what and why?

4. (optional) Appendix: vulnerabilities
   Instead of describing vulnerabilities that you came across as part of the motivation in your verdict in Section 2, you could also move the details of these vulnerabilities to an appendix, say in a numbered list, that you can then refer to in the `Verdict' section.

Pointers to code analysis tools

• RATS, which stands for "Rough Auditing Tool for Security" and ITS4, are very basic static checkers, which essentially uses grep aka CTRL-F to look for dangerous functionality.
• RIPS is a more modern open source scanner; development is currently on hold, but the latest version should still give interesting info.
• Information and links for a commercial source code evaluation tools will be emailed. This one is probably better to try out instead of RIPS

Misc sources of information about PHP

• php.net is good source of info, eg with a PHP manual which includes a chapter on security, a section on session handling
• MITRE has info on (CWE 661) Weaknesses in Software Written in PHP
• OWASP has a PHP project, which provides some info. OWASP also has a PHP Top 5
• The WACT project provides a lot of (pointers to) PHP-slanted security info
• PHP and the OWASP Top Ten Security Vulnerabilities
• The PHP security consortium (phpsec.org) has produced the PHP Security Guide and collects some pointers to other PHP security info;The website of the PHP security consortium hasn't been updated since 2006, so the initiative apparently died
• The book "19 Deadly Sins of Software Security" includes PHP-specific info on preventing SQL injection, XSS, Magic URLS and hidden form fields, and information leakage. The book is in the Nijmegen library under 8041HO and there is a copy in the "studielandschap" which cannot be lent out, so should always be there to have a read.
• XSS Cheat Sheet, not only for php but a general "cheat sheet" with vectors that successfully evaded common and uncommon XSS-protection mechanisms.

Documentation generation tools

• PHP Documenter
• Doxygen