alert tcp $EXTERNAL_NET 80 -> $HOME_NET any (msg:"ET MALWARE CommentCrew Possible APT c2 communications html return 1"; flow:established,to_client; content:"|48 54 54 50 2f 31 2e 30 20 32 30 30 20 4f 4b 0d 0a|"; content:"|43 6f 6e 74 65 6e 74 2d 4c 65 6e 67 74 68 3a 20 31 0d 0a|"; content:"|43 6f 6e 65 63 74 69 6f 6e 3a 20 4b 65 65 70 2d 41 6c 69 76 65 0d 0a|"; content:"|53 65 74 2d 43 6f 6f 6b 69 65 3a|"; content:"|0d 0a 20 31|"; classtype:targeted-activity; sid:2016477; rev:3; metadata:attack_target Client_Endpoint, created_at 2013_02_22, deployment Perimeter, confidence Medium, signature_severity Major, tag c2, updated_at 2019_07_26, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;)