alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Unknown Malvertising Payload CnC Checkin (PSecWin)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/?CheckApp"; http.user_agent; content:"Mozilla/4.0|20 28|compatible|3b 20|Win32|3b 20|WinHttp.WinHttpRequest.5|29|"; http.request_body; content:"|5c|PSecWin|0d 0a|"; fast_pattern; reference:md5,6bbbe6d8ca562449426f5f54e07f97db; classtype:trojan-activity; sid:2051091; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2024_02_26, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_02_26; target:src_ip;)