alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Backdoor.YesMaster CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.header; content:"x-user-agent|3a 20|YesMaster|0d 0a|"; fast_pattern; http.header_names; content:"|0d 0a|x-user-agent|0d 0a|"; content:"|0d 0a|x-whoami|0d 0a|"; content:"|0d 0a|x-pwd|0d 0a|"; content:"|0d 0a|x-hostname|0d 0a|"; content:"|0d 0a|x-isadm|0d 0a|"; content:"|0d 0a|x-is64Env|0d 0a|"; content:!"User-Agent"; reference:md5,4941501aca63cb8bdc86dadeffc9c29c; classtype:command-and-control; sid:2025157; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_12_20, deployment Perimeter, malware_family YesMaster, performance_impact Moderate, confidence High, signature_severity Major, updated_at 2020_08_24;)