diff --git a/detection-rules/link_self_sender_cred_theft_sus_tlds.yml b/detection-rules/link_self_sender_cred_theft_sus_tlds.yml new file mode 100644 index 00000000000..faac03583fe --- /dev/null +++ b/detection-rules/link_self_sender_cred_theft_sus_tlds.yml @@ -0,0 +1,34 @@ +name: "Link: Self-sender credential theft with suspicious TLD" +description: "Detects messages where the sender and recipient are the same, DMARC authentication passes, but the message contains links to suspicious top-level domains and shows machine learning indicators of credential theft intent." +type: "rule" +severity: "high" +source: | + type.inbound + // self sender + and sender.email.email == recipients.to[0].email.email + // auth passes + and coalesce(headers.auth_summary.dmarc.pass, false) + // link is suspicious tlds + and any(body.links, + .href_url.domain.tld in~ $suspicious_tlds + // and sender.email.domain.tld == .href_url.domain.tld + ) + // ML signals credential phishing + and any(ml.nlu_classifier(body.current_thread.text).intents, + .name == "cred_theft" and .confidence != "low" + ) + // exclude json attachments from legit services + // all will provide samples without attachments as well + and all(attachments, .file_extension != "json") +attack_types: + - "Credential Phishing" +tactics_and_techniques: + - "Social engineering" + - "Spoofing" +detection_methods: + - "Header analysis" + - "Sender analysis" + - "URL analysis" + - "Natural Language Understanding" + - "Threat intelligence" +id: "2221809b-f2d3-5323-973c-9fe46a969660"