alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE CryptoWall Check-in M2"; flow:established,to_server; urilen:<110; http.uri; pcre:"/[\/=][a-z0-9]{8,}$/"; http.accept; bsize:3; content:"|2a 2f 2a|"; http.content_type; bsize:33; content:"application/x-www-form-urlencoded"; http.header; content:" rv|3a|11.0"; fast_pattern; http.request_body; content:"="; offset:1; depth:1; pcre:"/^[a-z]=[a-f0-9]{80,}$/"; http.header_names; strip_pseudo_headers; to_lowercase; content:!"|0d 0a|accept-"; nocase; content:!"|0d 0a|referer|0d 0a|"; content:"|0d 0a|accept|0d 0a|content-type|0d 0a|"; startswith; reference:md5,3c53c9f7ab32a09de89bb44e5f91f9af; classtype:trojan-activity; sid:2020855; rev:6; metadata:created_at 2015_04_08, performance_impact Significant, signature_severity Major, updated_at 2024_05_04;)