ET MALWARE Phantom Captcha Client Checkin

Query · suricata

flow:established,to_server;
urilen:9;
http.method;
content:"GET";
http.uri;
content:"|2f|cptch|2f|"; fast_pattern; startswith;
pcre:"/^(?:[a-zA-Z0-9]{2})$/R";
target:src_ip;
Raw source ET MALWARE Phantom Captcha Client Checkin · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET MALWARE Phantom Captcha Client Checkin";
    flow:established,to_server;
    urilen:9;
    http.method;
    content:"GET";
    http.uri;
    content:"|2f|cptch|2f|"; fast_pattern; startswith;
    pcre:"/^(?:[a-zA-Z0-9]{2})$/R";
    reference:url,sentinelone.com/labs/phantomcaptcha-multi-stage-websocket-rat-targets-ukraine-in-single-day-spearphishing-operation/;
    reference:md5,61660f072008998bf57f8ad602408b68;
    classtype:command-and-control;
    sid:2065359; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state TLSDecrypt, created_at 2025_10_23, deployment Perimeter, deployment SSLDecrypt, confidence High, signature_severity Critical, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_23, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1071, mitre_technique_name Application_Layer_Protocol;
    target:src_ip;
)

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