[PR #3724] added rule: Brand impersonation: Sharepoint

Author: github-actions[bot]

detection-rules/3724_impersonation_sharepoint_body_credential_theft.yml

@@ -0,0 +1,153 @@
+name: "Brand impersonation: Sharepoint"
+description: |
+  Body, attached images or pdf contains a Sharepoint logo. The message contains a link and credential theft language.
+type: "rule"
+severity: "high"
+source: |
+  type.inbound
+  and length(body.links) > 0
+  and (
+    any(attachments,
+        (.file_type in $file_types_images or .file_type == "pdf")
+        and any(ml.logo_detect(.).brands, .name == "Microsoft SharePoint")
+    )
+    or any(ml.logo_detect(file.message_screenshot()).brands,
+           .name == "Microsoft SharePoint"
+    )
+    or strings.istarts_with(strings.replace_confusables(body.current_thread.text),
+                            "Sharepoint"
+    )
+    or regex.icontains(body.html.raw,
+                       '<img.*(title=|alt=).share.*src=""'
+    ) // broken Sharepoint logo
+    or (
+      strings.icontains(strings.replace_confusables(body.plain.raw), "SharePoint")
+      // message body references file deletion
+      and regex.icontains(body.plain.raw,
+                          '(expired )?file\s(was|has been|will be|scheduled (for|to be))\s?delet(ed|ion)'
+      )
+    )
+  )
+  and (
+    (
+      any(ml.nlu_classifier(body.current_thread.text).intents,
+          .name == "cred_theft" and .confidence == "high"
+      )
+      //
+      // This rule makes use of a beta feature and is subject to change without notice
+      // using the beta feature in custom rules is not suggested until it has been formally released
+      //
+      or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
+             .name == "cred_theft" and .confidence == "high"
+      )
+    )
+    or any(ml.nlu_classifier(body.current_thread.text).entities,
+           .name == "urgency" and strings.ilike(.text, "*encrypted*")
+    )
+    or any(body.links,
+           regex.imatch(.display_text,
+                        '(?:re)?view (?:(?:&|and) (?:e([[:punct:]]|\s)?)?sign )?(?:complete )?(?:document|file)'
+           )
+    )
+  )
+  and not (
+    (
+      (
+        strings.istarts_with(subject.subject, "RE:")
+        or strings.istarts_with(subject.subject, "R:")
+        or strings.istarts_with(subject.subject, "ODG:")
+        or strings.istarts_with(subject.subject, "答复:")
+        or strings.istarts_with(subject.subject, "AW:")
+        or strings.istarts_with(subject.subject, "TR:")
+        or strings.istarts_with(subject.subject, "FWD:")
+        or regex.imatch(subject.subject, '(\[[^\]]+\]\s?){0,3}(re|fwd?)\s?:')
+        or regex.imatch(subject.subject,
+                        '^\[?(EXT|EXTERNAL)\]?[: ]\s*(RE|FWD?|FW|AW|TR|ODG|答复):.*'
+        )
+      )
+      and (
+        (length(headers.references) > 0 or headers.in_reply_to is not null)
+        // ensure that there are actual threads
+        and (
+          length(body.previous_threads) > 0
+          or (length(body.html.display_text) - length(body.current_thread.text)) > 200
+        )
+      )
+    )
+  )
+  and (
+    profile.by_sender_email().prevalence != 'common'
+    or not profile.by_sender_email().solicited
+    or profile.by_sender().any_messages_malicious_or_spam
+  )
+  and not profile.by_sender().any_messages_benign
+  
+  // 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
+  )
+  
+  // negate sharepoint file share
+  and not (
+    // based on the message id format
+    (
+      (
+        strings.starts_with(headers.message_id, '<Share-')
+        and strings.ends_with(headers.message_id, '@odspnotify>')
+      )
+      or // negate legitimate access request to file
+   (
+        strings.starts_with(headers.message_id, '<Sharing')
+        and strings.ends_with(headers.message_id, '@odspnotify>')
+      )
+      // deal with Google thinking the message ID is "broke"
+      or (
+        strings.icontains(headers.message_id, 'SMTPIN_ADDED_BROKEN')
+        and any(headers.hops,
+                any(.fields,
+                    .name == "X-Google-Original-Message-ID"
+                    and strings.starts_with(.value, '<Share-')
+                    and strings.ends_with(.value, '@odspnotify>')
+                )
+        )
+      )
+    )
+    // all of the "action" links are sharepoint/ms
+    and all(filter(body.links,
+                   strings.icontains(subject.subject, .display_text)
+                   or .display_text == "Open"
+            ),
+            .href_url.domain.root_domain in ("sharepoint.com")
+            or (
+              .href_url.domain.tld == "ms"
+              // Microsoft does not own the .ms TLD, this checks to ensure it is one of their domains
+              and (
+                network.whois(.href_url.domain).registrant_company == "Microsoft Corporation"
+                or strings.ilike(network.whois(.href_url.domain).registrar_name,
+                                 "*MarkMonitor*",
+                                 "*CSC Corporate*",
+                                 "*com laude*"
+                )
+              )
+            )
+    )
+  )
+attack_types:
+  - "Credential Phishing"
+tactics_and_techniques:
+  - "Impersonation: Brand"
+  - "Social engineering"
+detection_methods:
+  - "Computer Vision"
+  - "Content analysis"
+  - "File analysis"
+  - "Natural Language Understanding"
+  - "Sender analysis"
+id: "fd6068f1-8c02-5f9b-a6e1-1292d7b59536"
+og_id: "284b1b70-8daa-5adf-9df8-15d4c6b5ead9"
+testing_pr: 3724
+testing_sha: 7ab74a78174293954773ebb20a5ae3ca03ec2fe0