alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Lyposit Ransomware Checkin 2"; flow:established,to_server; http.method; content:"GET"; nocase; http.uri; content:"/ad/?"; startswith; fast_pattern; pcre:"/^[a-z]{1,4}\x3d[a-z0-9]+?$/Ri"; http.header_names; content:!"User-Agent|0d 0a|"; classtype:command-and-control; sid:2015958; rev:4; metadata:attack_target Client_Endpoint, created_at 2012_11_29, deployment Perimeter, signature_severity Major, tag Ransomware, updated_at 2020_04_22, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)