alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE MSIL/TrojanDownloader.Agent.JVN CnC Checkin"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/?username="; bsize:<16; startswith; fast_pattern; pcre:"/^\/\x3fusername\x3d[a-z0-9]{2,3}_\d$/U"; http.connection; content:"Keep-Alive"; http.header_names; content:!"Referer"; content:!"User-Agent"; content:!"Accept"; reference:md5,f1006f3968f9edf76090e34702e647e6; reference:url,asec.ahnlab.com/ko/31703; classtype:trojan-activity; sid:2035368; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_03_01, deployment Perimeter, deprecation_reason Age, malware_family MSIL_TrojanDownloader_Agent_JVN, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_12_02, reviewed_at 2024_12_02;)