alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Unknown POST of System Info"; flow:established,to_server; http.method; content:"POST"; http.header; content:"X-ID|3a|"; http.request_body; content:"User is SYSTEM|3a|"; classtype:trojan-activity; sid:2016253; rev:4; metadata:created_at 2013_01_24, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_04_23;)