alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE TA399/Sidewinder Maldoc Activity"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/file.rtf"; endswith; fast_pattern; http.user_agent; content:"|3b 20|ms-office|3b 20|"; http.header_names; content:!"Referer"; reference:md5,e096b33467e6018944c05fb6e4bb03a0; reference:url,twitter.com/ShadowChasing1/status/1466001768765018116; classtype:trojan-activity; sid:2034569; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_12_01, deployment Perimeter, deployment SSLDecrypt, malware_family Sidewinder, performance_impact Low, confidence High, signature_severity Major, tag TA399, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_12_13, reviewed_at 2023_08_22;)