ET MALWARE Possible UNC1878/FIN12 Cobalt Strike CnC SSL Cert Inbound (office)

Query · suricata

flow:established,to_client;
tls.cert_subject;
content:"C=US, ST="; startswith;
content:", O=Office, OU=, CN="; nocase; fast_pattern;
tls.cert_issuer;
content:"C=US, ST="; startswith;
content:", O=Office, OU=, CN="; nocase;
Raw source ET MALWARE Possible UNC1878/FIN12 Cobalt Strike CnC SSL Cert Inbound (office) · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert tls $EXTERNAL_NET any -> $HOME_NET any (
    msg:"ET MALWARE Possible UNC1878/FIN12 Cobalt Strike CnC SSL Cert Inbound (office)";
    flow:established,to_client;
    tls.cert_subject;
    content:"C=US, ST="; startswith;
    content:", O=Office, OU=, CN="; nocase; fast_pattern;
    tls.cert_issuer;
    content:"C=US, ST="; startswith;
    content:", O=Office, OU=, CN="; nocase;
    reference:md5,880a45ff31bc540e80ecf2cf93134c12;
    reference:url,gist.github.com/aaronst/6aa7f61246f53a8dd4befea86e832456;
    reference:url,www.youtube.com/watch?v=BhjQ6zsCVSc;
    classtype:targeted-activity;
    sid:2031134; rev:3;
    metadata:attack_target Client_Endpoint, created_at 2020_10_29, deployment Perimeter, malware_family Cobalt_Strike, performance_impact Low, confidence Medium, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_11_19;
)

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