alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT/Bitter Related Checkin Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/userlog.php?id="; fast_pattern; content:"&&user="; distance:0; content:"&&OsI="; distance:0; http.header_names; content:!"User-Agent"; content:!"Referer"; reference:md5,cc7ddf9ed230ad4e060dfd0f32389efb; reference:url,twitter.com/ShadowChasing1/status/1478259210110775297; classtype:command-and-control; sid:2034876; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_01_10, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_01_10;)