alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ZLoader CnC Activity (POST)"; flow:established,to_server; urilen:1; http.header; content:"|0d 0a|Rand|3a 20|"; pcre:"/^[a-z]{32,255}[\r\n]/R"; http.header_names; bsize:56; content:"|0d 0a|host|0d 0a|user-agent|0d 0a|rand|0d 0a|connection|0d 0a|content-length|0d 0a 0d 0a|"; nocase; fast_pattern; reference:url,zscaler.com/blogs/security-research/inside-zloader-s-latest-trick-dns-tunneling; classtype:command-and-control; sid:2065738; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_11_12, deployment Perimeter, deployment SSLDecrypt, malware_family Zloader, confidence High, signature_severity Major, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_11_12, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol; target:src_ip;)