In association with heise online

25 April 2009, 15:24

Steer clear of JavaScript packers

  • Twitter
  • Facebook
  • submit to slashdot
  • StumbleUpon
  • submit to reddit

Paul Ducklin, Head of Technology for Sophos, a supplier of anti-virus software, says that developers of legitimate web applications should in future steer clear of tools for packing and encoding JavaScript. Ducklin is convinced that encrypting JavaScript code does more harm than good.

He said in his presentation, "The Malware in the Rue Morgue", at the RSA Conference that commercial packers like Aevita's Advanced HTML Encrypt and Password Protect gave hardly any protection against the theft of source code and web developers who thought they could effectively protect their creations against intellectual property theft using this or similar tools were on the wrong track. He demonstrated how source code encrypted with Aevita's tool could be converted into clear text within minutes using only freely available tools such as Mozilla's Rhino and Caffeine Monkey, along with his expertise in HTML and JavaScript.

Though relatively useless for protecting code, he said, encrypting played right into the hands of the cyber-criminals. That's because local security applications that constantly check web traffic coming from the internet to the browser for potential dangers either take considerably longer to analyse encrypted source code, adversely affecting the performance of web access, or collapse completely.

Ducklin said the Sophos anti-malware laboratory alone found 30,000 legitimate web sites daily that were infected with malicious JavaScript code or iFrames. Though many of these sites had been encrypted by their developers, it was obvious that less attention had been given to the security of the web server itself. Otherwise, attackers would not have succeeded in planting their malicious code. The record was scored, said Ducklin, by a web site whose code was infected with a range of malware from 22 different attackers.

He said that, besides their customary code obfuscation, attackers too were now using encryption techniques to secure their JavaScript code against analysis. He singled out one exploit tool kit in particular, Luckysploit, as worthy of mention because of its encryption techniques. He said, in combination with the coding of the legitimate, infected web site, this unnecessarily complicated the work of online scanners.

So Ducklin challenged the developer community to, in future, steer clear of the more than questionable notion of "security through obscurity". Sadly, the man from Sophos was unable to suggest any other way programmers could protect their valuable source code against unauthorised copying.

(Uli Ries)


Print Version | Send by email | Permalink:

  • July's Community Calendar

The H Open

The H Security

The H Developer

The H Internet Toolkit