alert tcp-pkt $HOME_NET any -> $EXTERNAL_NET !25 (msg:"ET RETIRED Win32/Wacatac.B!ml CnC Checkin"; flow:established,to_server; dsize:4; content:"|73 61 0d 0a|"; fast_pattern; flowbits:set,ET.Wacatac_B_Checkin; reference:md5,082ba31c83e3fc1114b6444111e88019; classtype:trojan-activity; sid:2037235; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_06_30, deployment Perimeter, former_category MALWARE, malware_family Wacatac_B_ml, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_09_17, reviewed_at 2024_09_17;)