IDS mailing list archives
Re: Obfuscated web pages
From: Kowsik <kowsik () gmail com>
Date: Thu, 14 Feb 2008 11:57:30 -0800
Signature-based ID/PS have little hope of catching these. Parsing HTTP responses (without javascript) is first of all pretty expensive, especially given chunked/transfer/content/mime encodings. On top of that parsing javascript is pretty much going to make the ID/PS performance go to hell. Could be wrong, but I highly doubt that anyone is actually doing a full HTML/Javascript parsing to determine that the impact is. You will need to embed a full DOM parser and a Javascript engine (like spider monkey) to make sense of what the code is trying to do. They you need to take into account IE/Firefox/Opera/Safari/etc idiosyncrasies. *sigh* The network would be the wrong place to try and defend against these, IMHO. K. On Thu, Feb 14, 2008 at 10:44 AM, Gary Flynn <flynngn () jmu edu> wrote:
Are any current network based IDS/P systems able to unwind obfuscated web script to examine the final javascript product? It would seem they would have to have a javascript engine to do so and issues with reassembly, iterations, and delays would preclude them from doing it inline. Without this capability, it would seem that network based IDS/IPS is destined to digress to AV style malware signatures for malicious web server issues and that the only reliable place to do IDS/P would be on the host. We've been seeing more and more obfuscated web script and according to a recently released IBM report, the majority of exploits are taking this path. http://www.iss.net/x-force_report_images/2008/index.html Thoughts? -- Gary Flynn Security Engineer James Madison University www.jmu.edu/computing/security
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Current thread:
- Obfuscated web pages Gary Flynn (Feb 14)
- Re: Obfuscated web pages Tim (Feb 14)
- Re: Obfuscated web pages Gary Flynn (Feb 14)
- Re: Obfuscated web pages Jon Oberheide (Feb 15)
- Re: Obfuscated web pages Dustin D. Trammell (Feb 15)
- Re: Obfuscated web pages Gary Flynn (Feb 14)
- Re: Obfuscated web pages Kowsik (Feb 14)
- RE: Obfuscated web pages Libershal, David M. (Feb 14)
- Re: Obfuscated web pages Gary Flynn (Feb 14)
- Re: Obfuscated web pages Stefano Zanero (Feb 19)
- Re: Obfuscated web pages Gary Flynn (Feb 14)
- Re: Obfuscated web pages Arian J. Evans (Feb 14)
- Re: Obfuscated web pages Mike Lococo (Feb 14)
- RE: Obfuscated web pages Mike Barkett (Feb 15)
- Re: Obfuscated web pages Ivan Arce (Feb 21)
- RE: Obfuscated web pages Mike Barkett (Feb 25)
- Re: Obfuscated web pages Ivan Arce (Feb 29)
- RE: Obfuscated web pages Mike Barkett (Feb 15)
- Re: Obfuscated web pages Tim (Feb 14)