alert http [$HTTP_SERVERS,$HOME_NET] any -> $EXTERNAL_NET any (msg:"ET ATTACK_RESPONSE Possible /etc/shadow via HTTP M2"; flow:established,to_client; http.response_body; content:"root|3a 21 3a|"; fast_pattern; content:"|3a|0|3a|"; within:9; content:"|3a 3a 3a 0a|"; within:17; reference:url,linuxize.com/post/etc-shadow-file/; classtype:successful-recon-limited; sid:2049388; rev:1; metadata:attack_target Server, created_at 2023_11_29, deployment Perimeter, performance_impact Low, confidence Low, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_11_29, mitre_tactic_id TA0003, mitre_tactic_name Persistence, mitre_technique_id T1505, mitre_technique_name Server_Software_Component;)