diff --git a/detection-rules/abuse_docsend_new_domain.yml b/detection-rules/abuse_docsend_new_domain.yml new file mode 100644 index 00000000000..48d295da824 --- /dev/null +++ b/detection-rules/abuse_docsend_new_domain.yml @@ -0,0 +1,37 @@ +name: "Service Abuse: DocSend Share From Newly Registered Domain" +description: "This Attack Surface Reduction (ASR) rule matches on DocSend notifications with recently registered reply-to domains." +type: "rule" +severity: "high" +source: | + type.inbound + + // Legitimate DocSend sending infratructure + and sender.email.email == "no-reply@docsend.com" + and headers.auth_summary.spf.pass + and headers.auth_summary.dmarc.pass + + // the message needs to have a reply-to address + and length(headers.reply_to) > 0 + + // reply-to email address has never received an email from your org + and not any(headers.reply_to, .email.email in $recipient_emails) + + // new reply-to + and any(headers.reply_to, + network.whois(.email.domain).days_old < 30 + ) +tags: + - "Attack surface reduction" +attack_types: + - "BEC/Fraud" + - "Credential Phishing" +tactics_and_techniques: + - "Evasion" + - "Free file host" + - "Impersonation: Brand" + - "Social engineering" +detection_methods: + - "Content analysis" + - "Header analysis" + - "Sender analysis" +id: "3bc152f2-6722-57be-b924-055c35fa1e60"