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Re: Proposed Sirefef (was Re: Late in the day...bet this could be sig'd)
From: Joel Esler <jesler () sourcefire com>
Date: Mon, 6 May 2013 13:37:13 -0400

On May 3, 2013, at 8:54 PM, lists () packetmail net wrote:
On 05/03/2013 05:57 PM, James Lay wrote:
https://blog.avast.com/2013/05/03/regents-of-louisiana-spreading-sirefef-malware/

YAY

James

Here's my go at it, I'm using Emerging-Threats[1] style/nomenclature not because
it's what's "right" but simply because it's what I'm acclimated to.  Please no
flamewar for cross-posting.  Gratuitous hex to avoid line-wrap.

alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET
CURRENT_EVENTS/VRT_COMMUNITY Potential Sirefef hostile executable served from
compromised or malicious WordPress site"; flow:established,from_server;
content:"/wp-content/"; http_uri; content:".exe|20|HTTP/1."; fast_pattern:only;
pcre:"/\/\d+\.exe$/U"; classtype:trojan-activity;
reference:url,blog.avast.com/2013/05/03/regents-of-louisiana-spreading-sirefef-malware;
sid:x; rev:1;)

Nathan,

Looking at what you are intending here, I think you mean it the other way (HOME_NET -> $EXTERNAL_NET)

I rewrote the rule to reflect that and put it in Malware-cnc.


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"ET
CURRENT_EVENTS/VRT_COMMUNITY Sirefef Fake Opera 10 User-Agent";
flow:established,to_server; content:"Opera/10|20|"; http_header;
fast_pattern:only; content:!"Accept"; http_header; classtype:trojan-activity;
reference:url,dev.opera.com/articles/view/opera-ua-string-changes; sid:x; rev:1;)

Adding this to the blacklist category.

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

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