alert http [$HOME_NET,$HTTP_SERVERS] any -> $EXTERNAL_NET any (msg:"ET ATTACK_RESPONSE Possible hosts File Output via HTTP (Windows Style)"; flow:established,to_client; http.response_body; content:!"<html"; content:"127.0.0.1"; content:"localhost|0d 0a|"; fast_pattern; within:11; pcre:"/^127\.0\.0\.1\s+localhost[\r\n]+/m"; classtype:successful-recon-limited; sid:2049403; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Server, created_at 2023_11_30, deployment Perimeter, performance_impact Low, confidence Low, signature_severity Major, tag WebShell, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_11_30, mitre_tactic_id TA0003, mitre_tactic_name Persistence, mitre_technique_id T1505, mitre_technique_name Server_Software_Component; target:src_ip;)