Re: Regarding GID 1, SID 33429 - Microsoft Windows SMB potential group policy fallback exploit attempt

["Al Lewis (allewi)" <allewi () cisco com>]

Hello Sandeep,

Can you provide a packet capture please?

Albert Lewis
QA Software Engineer
SOURCEfire, Inc. now part of Cisco
9780 Patuxent Woods Drive
Columbia, MD 21046
Phone: (office) 443.430.7112
Email: allewi () cisco com

From: Sandeep Singh [mailto:ctrlaltdelngone () gmail com]
Sent: Saturday, February 14, 2015 2:22 AM
To: Snort Users
Subject: [Snort-users] Regarding GID 1, SID 33429 - Microsoft Windows SMB potential group policy fallback exploit 
attempt

Hi all,
I am seeing a lot of noise for the recently pushed rule with GID 1, SID 33429 which works for detection of attempts 
towards vulnerability mentioned in MS15-014 (https://technet.microsoft.com/library/security/ms15-014.

Rule -->

alert tcp $HOME_NET any -> $HOME_NET [139,445] (msg:"OS-WINDOWS Microsoft Windows SMB potential group policy fallback 
exploit attempt"; flow:to_server,established; content:"|FF|SMB"; depth:4; offset:4; content:"|5C 
00|g|00|p|00|t|00|T|00|m|00|p|00|l|00|.|00|i|00|n|00|f|00 00|"; fast_pattern:only; detection_filter:track by_src,count 
5,seconds 2; metadata:policy balanced-ips alert, policy connectivity-ips alert, policy security-ips alert, service 
netbios-ssn; reference:cve,2015-0009; 
reference:url,technet.microsoft.com/en-us/security/bulletin/ms15-014<http://technet.microsoft.com/en-us/security/bulletin/ms15-014>;
 classtype:attempted-user; sid:33429; rev:1; )

From what I can understand from the rule and the alerts is that it triggers every time a computer tries to query a 
shared folder (which contains the group policies) for settings that applies to the current computer or user it fires an 
alarm which is of course causing huge number of false positives.

We are already in process of deploying an enterprise wide patch for MS15-014 but in the meantime is there anything that 
can be done to tune this detection rule.

If required I can provide a packet capture

Any suggestions?

Thanks

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