[Esd-l] Anyone got a procmail signature for Klez?

John D. Hardin jhardin at impsec.org
Wed May 1 19:52:01 PDT 2002

On Wed, 1 May 2002, Huba Leidenfrost wrote:

> On another list (unisog at sans.org) I just saw this:
> :0 B
> * AAAAAAAA2AAAAA4fug4AtAnNIbgBTM0hVGhpcyBwcm9ncmFtIGNhbm5vdCBiZSBydW
> /local/virus/klez
> This is found in the second line of some of the infected files.  Your
> procmail recipe 
> catches it on the first line and I haven't been able to find any that
> don't have both.  Adding this other line probably would not hurt.

Well, the reason I have a really short base64 signature is that is
enough (I think) to catch the magic that identifies the file as a
Windows executable. That, in combination with the audio/* MIME type
and the zero-size IFRAME + CID tag trap, should be enough to avoid
false positives, where a longer signature increases the vulnerability
to spoofing.

Somebody with a more intimate knowledge of Microsoft executable file
formats is welcome to comment...

 John Hardin KA7OHZ    ICQ#15735746    http://www.impsec.org/~jhardin/
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