alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Aibatook checkin 2"; flow:established,to_server; urilen:7; http.method; content:"GET"; http.uri; content:"/u.html"; fast_pattern; http.user_agent; content:"Mozilla/5.0 (compatible|3b 20|MSIE 10.0|3b 20|Windows NT 6.1|3b 20|Trident/6.0)"; startswith; http.header_names; content:!"Accept"; content:!"Referer|0d 0a|"; reference:url,welivesecurity.com/2014/07/16/win32aibatook/; reference:md5,d5e8adfefbcc3667734b8df4ae066be6; classtype:command-and-control; sid:2018687; rev:4; metadata:created_at 2014_07_17, malware_family Win32_Aibatook, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_09_24;)