Create open_redirect_smartadserver.yml

detection-rules/open_redirect_smartadserver.yml

@@ -0,0 +1,36 @@
+name: "Open Redirect: smartadserver.com"
+description: |
+  Message contains use of the smartadserver.com redirect. This has been exploited in the wild.
+type: "rule"
+severity: "medium"
+source: |
+  type.inbound
+  // smartadserver is used in benign messages, however, they commonly have many links
+  // ensure messages contain less than 20 links to ensure higher fidelity matching of malicious messages
+  and length(body.links) < 20
+  and any(body.links,
+      .href_url.domain.root_domain == "smartadserver.com"
+      and strings.icontains(.href_url.query_params, 'go=')
+      and not strings.icontains(.href_url.query_params,
+                                'go=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*smartadserver\.com(?:\&|\/|$)'
+      )
+  )
+  // remove uses that originate from smartadserver.com
+  and not any(headers.domains, .root_domain == "smartadserver.com")
+  // negate highly trusted sender domains unless they fail DMARC authentication
+  and (
+    (
+      sender.email.domain.root_domain in $high_trust_sender_root_domains
+      and not headers.auth_summary.dmarc.pass
+    )
+    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
+  )
+attack_types:
+  - "Credential Phishing"
+  - "Malware/Ransomware"
+tactics_and_techniques:
+  - "Open redirect"
+detection_methods:
+  - "Sender analysis"
+  - "URL analysis"
+id: "27e5a585-891d-549d-af34-e2b8dff6d64e"