alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET RETIRED Vidar Stealer CnC Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/"; http.header; content:"|0d 0a|X-Id|3a 20|"; fast_pattern; pcre:"/^[a-f0-9]{32}\r\n/R"; http.header_names; content:"|0d 0a|X-ID|0d 0a|User-Agent|0d 0a|Host|0d 0a 0d 0a|"; content:!"Referer"; classtype:trojan-activity; sid:2044788; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_03_27, deployment Perimeter, former_category MALWARE, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_09_30, reviewed_at 2024_09_30; target:src_ip;)