When we got contacted by ISC reader Greg in Hungary, whose web server had been hacked and adorned with a couple of obfuscated JavaScript files, we expected a variant of the "nmidahena" injection and a closed case. JavaScript is an interpreted language, and while the obfuscation attempts we see are getting more creative, the scripts can usually still be coerced quite easily into divulging their secrets. ISC handler Lenny Zeltser teaches the SANS course on malware analysis, and ISC handler Bojan Zdrnja wrote the portion on JavaScript analysis for that course, so we are usually able to make short work of bad stuff.
Cool example of self-defending javascript malware.
