ET MALWARE Cobalt Strike Beacon Activity (GET)

Query · suricata

flow:established,to_server;
content:"|0d 0a|Cookie|3a 20|SSID="; fast_pattern;
pcre:"/^SSID=(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/C";
http.method;
content:"GET";
http.uri;
content:".css"; endswith;
http.header_names;
content:"User-Agent|0d 0a|Connection|0d 0a|Cache-Control|0d 0a 0d 0a|";
content:!"Referer";
Raw source ET MALWARE Cobalt Strike Beacon Activity (GET) · 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 -> $EXTERNAL_NET any (
    msg:"ET MALWARE Cobalt Strike Beacon Activity (GET)";
    flow:established,to_server;
    content:"|0d 0a|Cookie|3a 20|SSID="; fast_pattern;
    pcre:"/^SSID=(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/C";
    http.method;
    content:"GET";
    http.uri;
    content:".css"; endswith;
    http.header_names;
    content:"User-Agent|0d 0a|Connection|0d 0a|Cache-Control|0d 0a 0d 0a|";
    content:!"Referer";
    reference:md5,9e97ace1f585b0914f99fde7014ed8c5;
    classtype:trojan-activity;
    sid:2032335; rev:3;
    metadata:attack_target Client_Endpoint, created_at 2021_03_25, deployment Perimeter, performance_impact Significant, confidence Medium, signature_severity Major, tag c2, updated_at 2024_04_04, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
)

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