Monthly Archives: June 2011

Javascript security web

JQlog: JQuery Keylogger, or why not to trust your proxy admin.

Note that this post is for awareness and educational purposes only. I do not encourage, and cannot be held responsible for malicious actions using these tools.

The Internet, as it is today, is a mash-up of JavaScript enabled services, often included from external websites. Internet companies offer so-called widgets, which are JavaScript tools that can be used in your own page. Popular examples of this are site analytics (Omniture, Google Analytics, etc) or share-abilities (AddThis, AddToAny, …). It’s by overwriting Javascript libraries on a page, that we can do other things, such as recording keystrokes.

“Overwriting” javascript libraries, or rather “inserting javascript” can be done in several ways. Cross Site Scripting is one of them, but for the sake of this blog post, I will act as a malicious proxy administrator, and overwrite the Google Analytics DNS entry ( and “fake” the ga.js javascript file.

For this, you’d need only 2 files:

This javascript file, found here, holds 3 parts: JQuery, a base64 encoder and the keylogger code itself: read more »