alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/Agent.CTK Checkin"; flow:established,to_server; content:"861gLc"; startswith; content:"AnK"; distance:0; content:"AnK"; distance:0; content:"AnK1.2901AnK0901AnK"; endswith; fast_pattern; reference:md5,8b964c81520445c89f337bab7afe5329; classtype:trojan-activity; sid:2037750; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_07_12, deployment Perimeter, malware_family MSIL_Agent_CTK, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_07_12, reviewed_at 2024_01_02;)