ET MALWARE Cobalt Strike Activity (GET)

Query · suricata

flow:established,to_server;
http.method;
content:"GET";
http.uri;
content:"/image/"; startswith;
pcre:"/^[a-z]{256}\.gif$/R";
http.header;
content:"Accept|3a 20|text/html,application/xhtml+xml,application/xml|3b|q=0.9,*/*l|3b|q=0.8|0d 0a|"; fast_pattern;
Raw source ET MALWARE Cobalt Strike 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 -> $EXTERNAL_NET any (
    msg:"ET MALWARE Cobalt Strike Activity (GET)";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/image/"; startswith;
    pcre:"/^[a-z]{256}\.gif$/R";
    http.header;
    content:"Accept|3a 20|text/html,application/xhtml+xml,application/xml|3b|q=0.9,*/*l|3b|q=0.8|0d 0a|"; fast_pattern;
    reference:url,twitter.com/TheDFIRReport/status/1463175512000368640;
    reference:md5,36be5b491426de64f9ac85c50f85808c;
    classtype:trojan-activity;
    sid:2034540; rev:1;
    metadata:attack_target Client_Endpoint, created_at 2021_11_23, deployment Perimeter, deployment SSLDecrypt, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2021_11_23, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;
)

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