Snort mailing list archives
Re: Quick uricontent question
From: Joel Esler <jesler () sourcefire com>
Date: Wed, 19 Sep 2012 17:26:15 -0400
James, in this case %u and such are variable fields. (The theme is digits and the siteID is also digits if it's the first report) So, what you'd want is something like this: alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"MALWARE-CNC Win.Trojan.Zeroaccess variant outbound communication"; flow:to_server,established; content:"/counter.img?theme="; nocase; http_uri; content:"&digits="; nocase; http_uri; distance:0; content:"&siteId="; nocase; http_uri; distance:0; pcre:"/theme\=\d+\&digits\=/Ui"; metadata:policy balanced-ips drop, policy security-ips drop, service http; reference:url,www.sophos.com/en-us/why-sophos/our-people/technical-papers/zeroaccess-botnet.aspx; classtype:trojan-activity;) Now, I haven't tested this against any pcaps or samples, I simply wrote this freehand by looking at the pdf you linked there. I'll do some testing and we'll try and get this (or something very similar) out. -- Joel Esler Senior Research Engineer, VRT OpenSource Community Manager Sourcefire On Sep 19, 2012, at 4:32 PM, James Lay <jlay () slave-tothe-box net> wrote:
So...doing some reading: http://www.sophos.com/en-us/why-sophos/our-people/technical-papers/zeroaccess-botnet.aspx From the text: The first phone home mechanism is through a specially crafted HTTP Get Request that takes the following form: GET /<unique ID>/counter.img?theme=%u&digits=10&siteId=%u HTTP/1.1\r\n Host: <hostname>\r\n User-Agent: Opera/9 (Windows NT %u.%u; %s; %s) So far here's what I have: alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"INDICATOR-COMPROMISE ZeroAccess phone home"; content:"User-Agent|3a| Opera/9"; http_header; uricontent:"/counter.img?theme="; As I am reading the info on uricontent, the content is already normalized...does that mean I don't have to hex anything with "/counter.img?theme="? Or does it matter. Thanks all. James ------------------------------------------------------------------------------ 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/ _______________________________________________ Snort-sigs mailing list Snort-sigs () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-sigs http://www.snort.org Please visit http://blog.snort.org for the latest news about Snort!
------------------------------------------------------------------------------ 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/ _______________________________________________ Snort-sigs mailing list Snort-sigs () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-sigs http://www.snort.org Please visit http://blog.snort.org for the latest news about Snort!
Current thread:
- Quick uricontent question James Lay (Sep 19)
- Re: Quick uricontent question lists () packetmail net (Sep 19)
- Re: Quick uricontent question James Lay (Sep 19)
- Re: Quick uricontent question Joel Esler (Sep 20)
- Re: Quick uricontent question James Lay (Sep 19)
- Re: Quick uricontent question Joel Esler (Sep 19)
- Re: Quick uricontent question James Lay (Sep 19)
- Re: Quick uricontent question lists () packetmail net (Sep 19)
- Re: Quick uricontent question James Lay (Sep 19)
- Re: Quick uricontent question lists () packetmail net (Sep 19)