alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Colibri Loader Activity"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".php?type=check&uid="; fast_pattern; pcre:"/^[0-9A-F]{16,32}$/Rs"; http.user_agent; content:!"Mozilla"; content:!"Safari"; content:!"Opera"; pcre:"/^[A-Za-z0-9]{16,32}$/"; http.header_names; content:"|0d 0a|User-Agent|0d 0a|Host|0d 0a 0d 0a|"; bsize:22; content:!"Referer"; reference:md5,9bf1574b794c7937cdbd12a9ff6fba76; classtype:command-and-control; sid:2034049; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_09_29, deployment Perimeter, malware_family Win32_Colibri, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_29;)