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| Subject: | MIME filtering immune to new MyDoom |
|---|---|
| Date: | Tue, 22 Feb 2005 18:22:27 -0000 |
Well, the new MyDoom "was created by repackaging an older MyDoom
variant in an encrypted "wrapper" so that anti-virus software could
not recognise it" according to Techworld - seeing a red rag I quickly
checked my filtered folder and oopsie! Thar' she blows ...
According to Symantec the worm may send itself as a double-zipped
file (a zipfile within a zipfile) - if this is the "encrypted
wrapper" referred to by Techworld I can report it makes absolutely no
difference to the appearance of the worm from a MIME perspective:
Content-Disposition: attachment;
filename="instruction.zip"
XEsDBAoAAA [...etc...]
(first character changed to avoid tripping AV filters)
No need to change any settings (or update any sigs!) to detect this
one!
URLs:
http://securityresponse.symantec.com/avcenter/venc/data/w32.mydoom.bb@mm.html
http://www.techworld.com/security/news/index.cfm?NewsID=3163
http://www.cyberdelix.net/tech/filtering.htm
Stu
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Stuart Udall
stuart at@cyberdelix.dot net - http://www.cyberdelix.net/
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* Origin: lsi: revolution through evolution (192:168/0.2)
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