ET MALWARE Cobalt Strike Beacon Activity (GET)

Query · suricata

flow:established,to_server;
http.method;
content:"GET";
http.uri;
content:"/topstories"; bsize:11; fast_pattern;
http.cookie;
content:"__cfduid="; startswith;
pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/R";
http.user_agent;
content:"Mozilla/5.0|20 28|Windows NT 6.1|29 20|Gecko/14.0|20|Firefox/14.0"; bsize:52;
Raw source ET MALWARE Cobalt Strike Beacon Activity (GET) · Suricata
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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 -> $EXTERNAL_NET any (
    msg:"ET MALWARE Cobalt Strike Beacon Activity (GET)";
    flow:established,to_server;
    http.method;
    content:"GET";
    http.uri;
    content:"/topstories"; bsize:11; fast_pattern;
    http.cookie;
    content:"__cfduid="; startswith;
    pcre:"/^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/R";
    http.user_agent;
    content:"Mozilla/5.0|20 28|Windows NT 6.1|29 20|Gecko/14.0|20|Firefox/14.0"; bsize:52;
    reference:md5,432e0676db09997f78e133263737b401;
    reference:url,documents.trendmicro.com/assets/white_papers/wp-earth-baku-an-apt-group-targeting-indo-pacific-countries.pdf;
    classtype:trojan-activity;
    sid:2033927; rev:1;
    metadata:attack_target Client_Endpoint, created_at 2021_09_13, deployment Perimeter, deployment SSLDecrypt, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2021_09_13, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;
)

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