[Snort-sigs] Proposed Sirefef (was Re: Late in the day...bet this could be sig'd)

Joel Esler jesler at ...435...
Mon May 6 13:37:13 EDT 2013

On May 3, 2013, at 8:54 PM, lists at ...3397... 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;)


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

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