Speaker: Vlad Savitsky Working at Skype: vlad_savitsky ICQ: 205535814 firstname.lastname@example.org +38096 530 27 12
Challenge● http://google-gruyere.appspot.com/start● Gruyere /ɡruːˈjɛər/ - a small, cheesy web application that allows its users to publish snippets of text and store assorted files.● "Unfortunately," Gruyere has multiple security bugs ranging from cross-site scripting and cross- site request forgery, to information disclosure, denial of service, and remote code execution.The goal is to discover bugs in Gruyere.
Cross-site scripting (XSS)● Allows attackers to inject script into Web pages viewed by other users.● http://en.wikipedia.org/wiki/Cross-site_scripting
Handling Data Golden Rule● Store exactly what the user typed.● When handling and outputting text in HTML, you need to be careful that proper filtering or escaping is done.
1. User sends some data User Input DrupalUser Invalid Input Code Validated User Input Database
2. Attacker sends code 1. Input JS DrupalUser Code 2. Not Well Validated Input JS Database
3. User request a page 1. Request DrupalUser JS 3. Not Well Code Escaped Data 2. SQL-Query JS Database
Cross-site request forgery● Ability to run some actions at server accessing some URL.● Also known as a one-click attack or session riding and abbreviated as CSRF (pronounced sea-surf) or XSRF.● http://en.wikipedia.org/wiki/Cross-site_request_forgery
1. Find URL User Profile Save Save Delete Deletehttp://example.com/user/10/deletehttp://example.com/user/10/delete
2. Post URL Server 1. Post page User HTML page2. Send URL <img 3. Open URL src=”URL” />Admin
Arbitrary code execution● Ability to execute any commands of the attackers choice on a target machine or in a target process.● http://en.wikipedia.org/wiki/Arbitrary_code_execution
Session fixation● Session fixation attacks attempt to exploit the vulnerability of a system which allows one person to fixate (set) another persons session identifier (SID).● Most session fixation attacks are web based, and most rely on session identifiers being accepted from URLs (query string) or POST data.● http://en.wikipedia.org/wiki/Session_fixation
How to find XSRF?● Inspect hook_menu().● Inspect AJAX callbacks.● If secure tokens not used used then XSRF is possible● See drupal_get_token().
Access bypass● Check hook_permissions().● Search for permission names.● Check access_callbacks in hook_menu().● Check if code works correctly with other contributed modules and respects their access restrictions.
Code Execution● Search for eval, system and etc.● Check code includes.● Check if files with code could be executed.● Search for php input format for blocks, nodes, fields and etc.● Check if modules like devel, php and etc. enabled.● Check if uploading files with php-code is possible.
Goals of the security team● Resolve reported security issues.● Provide assistance for contributed module maintainers in resolving security issues.● Provide documentation on how to write secure code.● Provide documentation on securing your site.
How to report a security issue● Do not post in the issue tracker or discuss it in IRC.● Mail to email@example.com● Provide as many details as you can. At least: ● Drupal version and/or module version. ● Steps to reproduce the problem.● Do not disclose the vulnerability to anyone before the advisory is issued.● You will be credited in the security announcement.
How the security team works with issues?● Review the issue and evaluate the potential impact on all supported releases of Drupal.● If it is indeed a valid problem, the security team is mobilized to eliminate it.● New versions are created and tested.● New packages are created and uploaded to Drupal.org.● When an issue has been fixed, use all available communication channels to inform users of steps that must be taken to protect themselves.
Issues with contributed modules● The module maintainer is contacted with a deadline.● When the maintainer fixes the problem, the security team issues an advisory.● If the maintainer does not fix the problem within the deadline, an advisory is issued, recommending disabling the module and the project on Drupal.org is unpublished.
Additional Reading● Core Security Advisories http://drupal.org/security● Contributed Project Security Advisories http://drupal.org/security/contrib● The Drupal Security Team http://drupal.org/security-team● Secure confguration of your Drupal site http://drupal.org/security/secure-confguration● Writing secure code http://drupal.org/writing-secure-code● Cracking Drupal – The Drupal security book http://crackingdrupal.com/● This papers website http://drupalsecurityreport.org● OWASP Top Ten Project http://www.owasp.org/index.php/Category:OWASP_Top_Ten_Project