alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Suspected Brute Ratel CnC Activity (POST)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:!"?"; content:!"="; http.header_names; bsize:53; content:"|0d 0a|User-Agent|0d 0a|Host|0d 0a|Content-Length|0d 0a|Cache-Control|0d 0a 0d 0a|"; fast_pattern; http.host; content:!".opera.com"; endswith; http.user_agent; content:!"MSIE"; content:!"Mozilla/4."; http.request_body; pcre:"/^[A-Za-z0-9=+/\x22\x00]{100,1000}$/"; reference:url,unit42.paloaltonetworks.com/brute-ratel-c4-tool/; reference:md5,1b97637fd83abfb7ecab040a4cda2d52; reference:md5,35c16888bdda9dd254a978d3a7c9814e; reference:md5,40afe8c95a3517ad07d3700ad46c2664; reference:md5,229648443814814cde5f01bf0f577e29; reference:md5,35c16888bdda9dd254a978d3a7c9814e; classtype:command-and-control; sid:2037711; rev:2; metadata:attack_target Client_Endpoint, created_at 2022_07_07, deployment Perimeter, performance_impact Moderate, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_05_20;)