New rule: invoicera_infra_abuse.yml (#1089)

Co-authored-by: ID Generator <[email protected]>

detection-rules/invoicera_infra_abuse.yml

@@ -0,0 +1,44 @@
+name: "Invoicera infrastructure abuse"
+description: "This rule is tailored to flag infrastructural abuse involving Invoicera, a SaaS-based invoicing and billing platform, which has been identified as a tool in widespread spam and credential phishing campaigns."
+type: "rule"
+severity: "medium"
+source: |
+  type.inbound
+  and sender.email.domain.root_domain == "invoicera.com"
+  // suspicious recipient pattern
+  and (
+    length(recipients.to) == 0
+    or any(recipients.to, .email.domain.valid == false)
+    or length(recipients.bcc) > 0
+  )
+  // suspicious link
+  and (
+    any(body.links,
+        .href_url.domain.root_domain in $free_file_hosts
+        or .href_url.domain.domain in $free_file_hosts
+    )
+    or any(body.links,
+           .href_url.domain.root_domain in $free_subdomain_hosts
+           and .href_url.domain.subdomain is not null
+           and .href_url.domain.subdomain != "www"
+    )
+  )
+  // mismatched reply-to
+  and (
+    headers.return_path.email is not null
+    and headers.return_path.email != sender.email.email
+  )
+
+attack_types:
+  - "Credential Phishing"
+  - "Spam"
+tactics_and_techniques:
+  - "Free file host"
+  - "Free subdomain host"
+  - "Image as content"
+  - "Social engineering"
+detection_methods:
+  - "Content analysis"
+  - "Header analysis"
+  - "Sender analysis"
+id: "1e56f310-750b-5c26-84eb-63e78f20a6bd"