Create attachment_docx_hyperlink_targeting_recipient.yml

detection-rules/attachment_docx_hyperlink_targeting_recipient.yml

@@ -0,0 +1,29 @@
+name: "Attachment: DOCX with hyperlink targeting recipient address"
+description: "Detects DOCX attachments containing hyperlinks with anchor references that match recipient email addresses. This technique is commonly used to personalize malicious documents and evade detection."
+type: "rule"
+severity: "medium"
+source: |
+  type.inbound
+  and any(filter(attachments, .file_extension == 'docx'),
+          any(filter(file.explode(.), .file_name == 'word/document.xml'),
+                  any(regex.iextract(.scan.strings.raw,
+                                     '<w:hyperlink[^\>]*w:anchor="(?P<email_address>[^\"]+)"'
+                      ),
+                      .named_groups["email_address"] in map(recipients.to,
+                                                            .email.email
+                      )
+                  )
+          )
+  )
+
+attack_types:
+  - "Credential Phishing"
+  - "Malware/Ransomware"
+tactics_and_techniques:
+  - "Evasion"
+  - "Social engineering"
+detection_methods:
+  - "File analysis"
+  - "Archive analysis"
+  - "XML analysis"
+id: "9ec8fa49-bda9-5e8f-876f-1e53a46d83ca"