ET MALWARE Cobalt Strike Beacon Observed (MASB UA)

Query · suricata

flow:established,to_server;
http.method;
content:"GET";
http.user_agent;
content:"Mozilla/5.0|20|(compatible|3b 20|MSIE 9.0|3b 20|Windows NT|20|6.1|3b 20|WOW64|3b 20|Trident/5.0|3b 20|MASB)"; bsize:76; fast_pattern;
http.cookie;
pcre:"/^[a-zA-Z0-9/+]{171}=$/";
http.header_names;
content:!"Referer";
Raw source ET MALWARE Cobalt Strike Beacon Observed (MASB UA) · 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 -> $EXTERNAL_NET any (
    msg:"ET MALWARE Cobalt Strike Beacon Observed (MASB UA)";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.user_agent;
    content:"Mozilla/5.0|20|(compatible|3b 20|MSIE 9.0|3b 20|Windows NT|20|6.1|3b 20|WOW64|3b 20|Trident/5.0|3b 20|MASB)"; bsize:76; fast_pattern;
    http.cookie;
    pcre:"/^[a-zA-Z0-9/+]{171}=$/";
    http.header_names;
    content:!"Referer";
    reference:md5,8079676dd62582da4d2e9d2448c1142d;
    classtype:command-and-control;
    sid:2032945; rev:2;
    metadata:attack_target Client_Endpoint, created_at 2021_05_12, deployment Perimeter, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, tag c2, updated_at 2021_05_12, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;
)

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