ET MALWARE TA421/YTTRIUM/APT29 TLS Certificate M1

Query · suricata

flow:established,to_client;
tls.cert_subject;
content:"C=IL, O=StartCom Ltd., CN="; fast_pattern; startswith;
isdataat:!20,relative;
content:"CN=*"; endswith;
Raw source ET MALWARE TA421/YTTRIUM/APT29 TLS Certificate M1 · 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 TA421/YTTRIUM/APT29 TLS Certificate M1";
    flow:established,to_client;
    tls.cert_subject;
    content:"C=IL, O=StartCom Ltd., CN="; fast_pattern; startswith;
    isdataat:!20,relative;
    content:"CN=*"; endswith;
    reference:url,community.riskiq.com/article/541a465f;
    classtype:command-and-control;
    sid:2033632; rev:3;
    metadata:attack_target Client_and_Server, created_at 2021_07_31, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag SSL_Malicious_Cert, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_09_17;
)

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