ET MALWARE Cobalt Strike Malleable C2 OCSP Profile

Query · suricata

flow:to_server,established;
http.method;
content:"GET";
http.uri;
content:"/oscp/"; fast_pattern; depth:6;
pcre:"/^\/oscp\/[a-z]+$/";
http.header;
content:"Host|3a 20|ocsp.verisign.com|0d 0a|Accept"; depth:31;
content:"Microsoft-CryptoAPI/6.1";
http.header_names;
content:!"Referer|0d 0a|";
Raw source ET MALWARE Cobalt Strike Malleable C2 OCSP Profile · 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 -> $EXTERNAL_NET any (
    msg:"ET MALWARE Cobalt Strike Malleable C2 OCSP Profile";
    flow:to_server,established;
    http.method;
    content:"GET";
    http.uri;
    content:"/oscp/"; fast_pattern; depth:6;
    pcre:"/^\/oscp\/[a-z]+$/";
    http.header;
    content:"Host|3a 20|ocsp.verisign.com|0d 0a|Accept"; depth:31;
    content:"Microsoft-CryptoAPI/6.1";
    http.header_names;
    content:!"Referer|0d 0a|";
    reference:md5,2ba2e7af1246da08e4fd7345c7207b59;
    reference:url,github.com/rsmudge/Malleable-C2-Profiles/blob/master/normal/oscp.profile;
    classtype:command-and-control;
    sid:2032750; rev:3;
    metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2017_05_15, deployment Perimeter, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2020_08_06, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;
)

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