alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/Khonsri Ransomware CnC Activity"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/zambos_caldo_de_p.txt"; startswith; fast_pattern; http.header_names; content:!"User-Agent"; reference:url,businessinsights.bitdefender.com/technical-advisory-zero-day-critical-vulnerability-in-log4j2-exploited-in-the-wild; classtype:command-and-control; sid:2034723; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_12_14, deployment Perimeter, malware_family MSIL_Khonsri, performance_impact Low, confidence High, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_12_14, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;)