alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Bisonal RC4 Encrypted 8 Byte Static CnC Checkin"; flow:established,to_server; urilen:<100; http.method; content:"POST"; http.request_body; content:"|81 b2 a8 97 7e a3 1b 91|"; startswith; fast_pattern; endswith; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; content:!"|0d 0a|accept"; reference:md5,CC71620DE7216B186DA2C9BA06703613; reference:url,researchcenter.paloaltonetworks.com/2018/07/unit42-bisonal-malware-used-attacks-russia-south-korea/; classtype:command-and-control; sid:2025923; rev:5; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_07_31, deployment Perimeter, malware_family Bisonal, performance_impact Low, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_05_01;)