ET ATTACK_RESPONSE KoiStealer Payload Inbound

Query · suricata

flow:established,to_client;
http.response_body;
content:"Add|2d|Type|20 2d|TypeDefinition|20 40|"; startswith; fast_pattern;
content:"|20 20 20|CONTEXT|5f|i386|20 3d 20|0x10000";
content:"|20 20 20|CONTEXT|5f|i486|20 3d 20|0x10000|2c 20 20 20 2f 2f 20 20|same|20|as|20|i386";
content:"CONTEXT_CONTROL";
content:"CONTEXT_INTEGER";
target:dest_ip;
Raw source ET ATTACK_RESPONSE KoiStealer Payload Inbound · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET ATTACK_RESPONSE KoiStealer Payload Inbound";
    flow:established,to_client;
    http.response_body;
    content:"Add|2d|Type|20 2d|TypeDefinition|20 40|"; startswith; fast_pattern;
    content:"|20 20 20|CONTEXT|5f|i386|20 3d 20|0x10000";
    content:"|20 20 20|CONTEXT|5f|i486|20 3d 20|0x10000|2c 20 20 20 2f 2f 20 20|same|20|as|20|i386";
    content:"CONTEXT_CONTROL";
    content:"CONTEXT_INTEGER";
    classtype:trojan-activity;
    sid:2064144; rev:1;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state plaintext, created_at 2025_08_25, deployment Perimeter, malware_family KoiStealer, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_08_25, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1105, mitre_technique_name Ingress_Tool_Transfer;
    target:dest_ip;
)

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