alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Backdoor Checkin (POST)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/?id="; startswith; http.header_names; content:!"Referer|0d 0a|"; http.request_body; content:"SU5JVCUl"; startswith; fast_pattern; reference:md5,341610a5a0cc430f99f9f9bd694b04a9; classtype:command-and-control; sid:2035641; rev:3; metadata:attack_target Client_Endpoint, created_at 2022_03_29, deployment Perimeter, deployment SSLDecrypt, malware_family Win32_Backdoor, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_03_30;)