[Snort-sigs] SID 13923 - Bad Rule

evilghost at ...3397... evilghost at ...3397...
Tue Apr 6 15:10:15 EDT 2010

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 at ...3397... 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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