[Snort-sigs] Trojan.APT.Seinup sig with pcre help request

Joel Esler jesler at ...435...
Fri Jun 21 11:27:57 EDT 2013


Is there a minimum length to the query here?  for the use of urilen?  ".php" is a content match that will enter all the time.  Trying to scrounge up ways of making this faster.


On Jun 21, 2013, at 11:14 AM, James Lay <jlay at ...3266...> wrote:

> On 2013-06-19 12:07, James Lay wrote:
>> This one hurt my head:
>> 
>> alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS 
>> (msg:"MALWARE-CNC
>> Trojan.Win32.APT.Seinup outbound connection";
>> flow:to_server,established; content:"php|3f|"; http_uri;
>> pcre:"/\x2ephp\x3fa-z0-9]{11,13}=[a-z0-9]{3,7}\x26/"; metadata:policy
>> balanced-ips drop, policy security-ips drop, service http;
>> 
>> reference:url,http://www.fireeye.com/blog/technical/malware-research/2013/06/trojan-apt-seinup-hitting-asean.html;
>> 
>> classtype:trojan-activity; sid:10000081; rev:1;)
>> 
>> Is that PCRE too beefy?  I didn't go the full length of the url..it's
>> pretty nuts.  Thanks for any help on this all.
>> 
>> James
>> 
> 
> And yet another fix...thanks to those that have helped out:
> 
> alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"MALWARE-CNC 
> Trojan.Win32.APT.Seinup outbound connection"; 
> flow:to_server,established; content:".php|3f|"; http_uri; 
> pcre:"/\x2ephp\x3f[a-z0-9]{11,13}=[a-z0-9]{3,7}\x26[a-z0-9]{3,5}=[a-z0-9]{48}\x26[a-z0-9]{7,9}=[a-z0-9]{32}\x26[a-z0-9]{14,16}=/iU"; 
> metadata:policy balanced-ips drop, policy security-ips drop, service 
> http; 
> reference:url,http://www.fireeye.com/blog/technical/malware-research/2013/06/trojan-apt-seinup-hitting-asean.html; 
> classtype:trojan-activity; sid:10000081; rev:3;)
> 
> James
> 
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