ET MALWARE HTA.BabyShark Checkin

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE HTA.BabyShark Checkin";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/expres.php?op="; fast_pattern;
    pcre:"/^\d/R";
    http.user_agent;
    content:"Mozilla/4.0 (compatible|3b 20|Win32|3b 20|WinHttp.WinHttpRequest.5)";
    http.referer;
    content:".hta";
    reference:md5,94b60cf91e550e1d981aaf9962d52e18;
    classtype:command-and-control;
    sid:2027365; rev:3;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_05_20, deployment Perimeter, malware_family BabyShark, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_28;
)