alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/image/"; startswith; pcre:"/^[a-z]{256}-\.jpg$/R"; http.header_names; strip_pseudo_headers; to_lowercase; content:"|0d 0a|referer|0d 0a|accept|0d 0a|pragma|0d 0a|cache-control|0d 0a|"; startswith; fast_pattern; reference:md5,e31a96ce2760c27a4f1cf83a0b5da83b; reference:url,twitter.com/malwrhunterteam/status/1425771461499920385; classtype:trojan-activity; sid:2034474; rev:4; metadata:attack_target Client_Endpoint, created_at 2021_11_16, deployment Perimeter, deployment SSLDecrypt, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2024_04_26, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;)