alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Ursnif Variant CnC Beacon"; flow:established,to_server; urilen:>125; http.method; content:"GET"; http.uri; content:"/assets/"; fast_pattern; content:"."; distance:100; pcre:"/\/assets(?:\/[a-zA-Z0-9_]+)+\.(?:jpeg|gif)$/"; http.header_names; content:!"Accept"; content:!"Referer|0d 0a|"; http.user_agent; pcre:"/^(?:Mozilla\/|Shockwave)/i"; reference:md5,4dbff312f5ee5bfbd757030109faec2d; classtype:command-and-control; sid:2023870; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_02_06, deployment Perimeter, malware_family ursnif, performance_impact Significant, confidence High, signature_severity Major, tag c2, updated_at 2024_04_22, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)