alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/Alcatrez Locker Ransomware CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?user="; fast_pattern; content:"&try="; distance:0; content:"&status="; distance:0; http.header_names; content:"|0d 0a|Host|0d 0a|Connection|0d 0a 0d 0a|"; startswith; http.connection; content:"Keep-Alive"; bsize:10; nocase; reference:md5,1cb51c130e6f75f11c095b122e008bbc; classtype:command-and-control; sid:2023506; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_11_14, deployment Perimeter, malware_family Ransomware, malware_family Alcatrez_Locker, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_03, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)