Re: RAR File Detection

["Ginski, Richard" <richard.ginski () urs com>]

The packet capture to determine payload was performed using WireShark.






Richard Ginski, CISSP
URS  |  IT Corporate Security, Security Engineer |  7650 West Courtney Campbell Causeway, Tampa, FL  33607
| desk 813.675.6851


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From: James Lay [mailto:jlay () slave-tothe-box net]
Sent: Friday, October 11, 2013 8:10 PM
To: Snort-Sigs
Subject: Re: [Snort-sigs] RAR File Detection


On Oct 11, 2013, at 1:19 PM, "Ginski, Richard" <richard.ginski () urs com<mailto:richard.ginski () urs com>> wrote:


Hi,

I am new to the list and fairly-new to SNORT rule writing.

I am trying to create a snort rule that detects "rar" files exiting our network...regardless of protocol/service. (I am 
assuming clear text-type protocols will only work here.) I am unable to create a rule that will fire on the criteria I 
have supplied for that rule.

In the content of the rule, I have tried using hex ("52 61 72 21 1A 07" to cover both versions of rar)  and also ascii 
("Rar!", with case sensitivity enabled/disabled). I did not define depth nor offset so that the entire payload is 
examined. I also performed a packet capture to confirm that both values for content exist in the payload of the packet 
capture. Further, to eliminate them as a potential cause, I also have replaced the variables with known IP values of 
the traffic captured. Still no luck.

Below are the rules I've tried:

alert tcp $HOME_NET any -> $EXTERNAL_NET any (sid:1002235; gid:1; content:"|52 61 72 21 1A 07|"; msg:"RAR file 
Detected_Testing_Please Ignore"; classtype:Test; rev:40; )

alert tcp $HOME_NET any -> $EXTERNAL_NET any (sid:1002235; gid:1; content:"Rar!"; msg:"RAR file Detected_Testing_Please 
Ignore"; classtype:Test; rev:40; )

Richard Ginski, CISSP
URS  |  IT Corporate Security, Security Engineer |  7650 West Courtney Campbell Causeway, Tampa, FL  33607
| desk 813.675.6851



Live traffic or pcap testing?  If pcap add a -k none to your snort line.

James

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