alert http any any -> [$HTTP_SERVERS,$HOME_NET] any (msg:"ET EXPLOIT Klog Server Command Injection Inbound (CVE-2021-3317)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/async.php?action="; content:"&source=|3b|"; fast_pattern; reference:cve,2021-3317; classtype:attempted-admin; sid:2032638; rev:1; metadata:attack_target Server, created_at 2021_04_09, cve CVE_2021_3317, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_04_09, mitre_tactic_id TA0008, mitre_tactic_name Lateral_Movement, mitre_technique_id T1210, mitre_technique_name Exploitation_Of_Remote_Services;)