alert tcp-pkt $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Shark Stealer CnC Checkin"; flow:established,to_server; dsize:<50; content:"data|3a|"; startswith; content:"|3a|shark|5f|"; fast_pattern; reference:md5,8ec92ce467117d0616d9728c3141004c; reference:url,otx.alienvault.com/pulse/68fb82aa72486ffb1983f5f5; classtype:trojan-activity; sid:2065384; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, created_at 2025_10_24, deployment Perimeter, malware_family SharkStealer, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_24, mitre_tactic_id TA0009, mitre_tactic_name Collection, mitre_technique_id T1005, mitre_technique_name Data_from_local_system; target:src_ip;)