Snort mailing list archives

Re: RE : FP with pcre P and http_client_body + distance 0 ?


From: Joel Esler <jesler () sourcefire com>
Date: Sun, 22 Jul 2012 08:16:26 -0400

Remove distance:0 and try again. 

--
Joel Esler
Senior Research Engineer, VRT
OpenSource Community Manager

On Jul 22, 2012, at 3:46 AM, "rmkml () yahoo fr" <rmkml () yahoo fr> wrote:

and Snort not fire (confirm bug) If you remove http_client_body/P options like this:
 alert tcp any any -> any 80 (msg:"test http_client_body wrong order"; flow:to_server,established; content:"aaa="; 
depth:4; offset:0; pcre:"/eee=/"; content:"ccc="; distance:0; classtype:attempted-admin; sid:8890829; rev:1; )
Regards
Rmkml



-------- Original message -------- Subject: FP with pcre P and http_client_body + distance 0 ? From: Rm Kml To: 
Snort-devel () lists sourceforge net CC: rmkml () yahoo fr 

Hi,

First, Congratulations for last Snort v2.9.3!

Ok maybe you have a FP with rule:
 alert tcp any any -> any 80 (msg:"test http_client_body wrong order"; flow:to_server,established; content:"aaa="; 
depth:4; offset:0;
http_client_body; pcre:"/eee=/P"; content:"ccc="; distance:0; http_client_body; classtype:attempted-admin; 
sid:8890829; rev:1; )
-> Snort fire! (but it's not true)


Another rule for checking and snort not fire and it's true:
 alert tcp any any -> any 80 (msg:"test http_client_body wrong order"; flow:to_server,established; content:"aaa="; 
depth:4; offset:0;
http_client_body; content:"eee="; distance:0; http_client_body; content:"ccc="; distance:0; http_client_body; 
classtype:attempted-admin;
sid:8890828; rev:1; )

Another testing for checking and snort fire and it's true:
 alert tcp any any -> any 80 (msg:"test http_client_body right order"; flow:to_server,established; content:"aaa="; 
depth:4; offset:0;
http_client_body; pcre:"/ccc=/P"; content:"eee="; distance:0; http_client_body; classtype:attempted-admin; 
sid:8890830; rev:1; )

Tested with this wget cmd line:
 wget --post-data="aaa=bbb&ccc=ddd&eee=fff" http://www.kernel.org/abc.html

Please Credits to rmkml.
Thx Suricata engine [OISF] for confirmed this.
Regards
Rmkml

http://twitter.com/rmkml

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Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
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