ET MALWARE TransferLoader Custom HTTP Header and Values Observed (X-Custom-Header)

Query · suricata

flow:established,to_server;
http.header;
content:"X-Custom-Header|3a 20|"; fast_pattern;
pcre:"/^(?:unknown|xxx)/R";
target:src_ip;
Raw source ET MALWARE TransferLoader Custom HTTP Header and Values Observed (X-Custom-Header) · 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 TransferLoader Custom HTTP Header and Values Observed (X-Custom-Header)";
    flow:established,to_server;
    http.header;
    content:"X-Custom-Header|3a 20|"; fast_pattern;
    pcre:"/^(?:unknown|xxx)/R";
    reference:url,www.zscaler.com/blogs/security-research/technical-analysis-transferloader;
    classtype:trojan-activity;
    sid:2063155; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, affected_product Windows_11, attack_target Client_and_Server, tls_state TLSDecrypt, created_at 2025_06_23, deployment Perimeter, malware_family TransferLoader, performance_impact Low, confidence High, signature_severity Major, updated_at 2025_06_23, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
    target:src_ip;
)

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