ET MALWARE LegionLoader Activity Observed (LegionClient)

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE LegionLoader Activity Observed (LegionClient)";
    flow:established,to_server;
    http.method;
    content:"POST";
    http.uri;
    content:"/api-v1";
    http.user_agent;
    content:"LegionClient"; fast_pattern;
    http.header_names;
    content:!"Referer";
    content:"|0d 0a|pauthx|0d 0a|";
    classtype:trojan-activity;
    sid:2046298; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_06_16, deployment Perimeter, deployment SSLDecrypt, malware_family LegionLoader, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_06_22, reviewed_at 2025_07_14;
    target:src_ip;
)