alert http any any -> $HOME_NET any (msg:"ET MALWARE Win32/frebniis IIS Backdoor Trigger Attempt M2"; flow:established,to_server; http.method; content:"POST"; http.uri; content:".aspx"; http.request_body; content:"7ux4398!"; fast_pattern; reference:url,symantec-enterprise-blogs.security.com/blogs/threat-intelligence/frebniis-malware-iis; classtype:trojan-activity; sid:2044232; rev:2; metadata:attack_target Web_Server, created_at 2023_02_16, deployment Perimeter, deployment Internal, deployment SSLDecrypt, malware_family Win32_frebniis, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_04_03, reviewed_at 2025_07_14;)