Win.Trojan.Kovtar

[Y M <snort () outlook com>]

Hello,


Below two signatures detect the initial JS downloader and post-infection C&C.


alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"MALWARE-CNC Win.Trojan.Kovter variant JS downloader outbound 
connection"; flow:to_server,established; urilen:<100; content:"GET"; http_method; content:"/counter/?"; 
fast_pattern:only; http_uri; content:"UA-CPU|3A 20|"; http_header; content:"MSIE 7.0|3B|"; http_header; 
content:!"Referer"; http_header; pcre:"/\/counter\/\x3f\w+/U"; metadata:ruleset community, service http; 
classtype:trojan-activity; sid:1000821; rev:1;)

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"MALWARE-CNC Win.Trojan.Kovter variant outbound connection"; 
flow:to_server,established; dsize:55<>205; content:!" HTTP/"; content:"|00 00 00|"; offset:1; metadata:ruleset 
community; classtype:trojan-activity; sid:1000822; rev:1;)


Thank you.

YM

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