ET MALWARE Oyster Backdoor CnC Checkin M6

Query · suricata

flow:established,to_server;
urilen:<30;
http.method;
content:"POST";
http.uri;
content:"/api/"; startswith;
http.user_agent;
content:"Mozilla|2f|6|2e|0|20 28|"; startswith; fast_pattern;
http.header_names;
content:!"|0d 0a|auth|0d 0a|"; nocase;
content:!"|0d 0a|x-"; nocase;
content:!"|0d 0a|referer|0d 0a|"; nocase;
target:src_ip;
Raw source ET MALWARE Oyster Backdoor CnC Checkin M6 · 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 Oyster Backdoor CnC Checkin M6";
    flow:established,to_server;
    urilen:<30;
    http.method;
    content:"POST";
    http.uri;
    content:"/api/"; startswith;
    http.user_agent;
    content:"Mozilla|2f|6|2e|0|20 28|"; startswith; fast_pattern;
    http.header_names;
    content:!"|0d 0a|auth|0d 0a|"; nocase;
    content:!"|0d 0a|x-"; nocase;
    content:!"|0d 0a|referer|0d 0a|"; nocase;
    reference:md5,5c44fcd4914bd2114c9f150284111f4d;
    classtype:command-and-control;
    sid:2065048; 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_03, deployment Perimeter, deployment SSLDecrypt, malware_family Oyster_Backdoor, performance_impact Moderate, confidence High, signature_severity Critical, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_03, 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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