ET MALWARE Suspected TA451 Related FalseFont Backdoor Activity M4

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE Suspected TA451 Related FalseFont Backdoor Activity M4";
    flow:established,to_server;
    urilen:<37;
    http.uri;
    content:"/api/Core/Command/Add/Schedule/"; startswith; fast_pattern;
    pcre:"/^(?:True|False)$/R";
    http.header_names;
    content:!"User-Agent|0d 0a|";
    content:!"Referer|0d 0a|";
    content:"Authorization|0d 0a|";
    threshold:type limit, count 1, seconds 300, track by_src;
    reference:url,nextron-systems.com/2024/01/29/analysis-of-falsefont-backdoor-used-by-peach-sandstorm-threat-actor/;
    reference:md5,6fd5d31d607a212c6f7651c79e7655a3;
    classtype:misc-activity;
    sid:2050676; rev:2;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2024_02_01, deployment Perimeter, malware_family FalseFont, confidence High, signature_severity Critical, tag TA451, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_02_05;
)