Snort mailing list archives

Re: SID 13923 - Bad Rule


From: "evilghost () packetmail net" <evilghost () packetmail net>
Date: Tue, 6 Apr 2010 14:10:15 -0500

Oh yeah, this one is policy security-ips drop so you may want to 
escalate priority.  I don't think SMTP is that nefarious, SF you might 
have some appliance IPS impacted customers...

-evilghost

evilghost () packetmail net wrote:
Hello, SID 13923 seems to generate quite a lot of false positives.  
Looking at the rule, did you really mean it this way?

content:"HELO "; content:!"|00|"; within:2

This fires on every SMTP HELO since the syntax is "HELO 
fqdn.hostname.com".  I would imagine any RFC compliant SMTP connection 
with "HELO" would cause this signature to fire.  I would expect to not 
find a null character after the SMTP "HELO" verb within three bytes of 
the previous content match (taking into account the 0x20 after the HELO 
verb).

Can this be addressed?  As-is it appears this signature isn't specific 
to CVE 2006-3277 at all.

Not to be an jerk but this really is a horrid rule, how did it make it 
into this VRT release?  It was modified in this VRT release.

Thanks,
-evilghost




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See why Intel Parallel Studio got high marks during beta.
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