Merge branch 'main' into patch-81

detection-rules/impersonation_recipient_domain_display_name.yml

@@ -0,0 +1,77 @@
+name: "Display name impersonation using recipient SLD (new sender)"
+description: |
+  The recipient domain's SLD is used in the sender's display name
+  in order to impersonate the organization. 
+type: "rule"
+severity: "medium"
+source: |
+  type.inbound
+  and (
+    // recipient SLD is being impersonated in the subject + display name
+    (
+      // these are usually targeted with just 1 recipient,
+      // but sometimes they CC themselves or have a blank CC
+      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
+      and any(recipients.to,
+              // ensure that we're checking the org SLD
+              .email.domain.sld in $org_slds
+              and strings.icontains(sender.display_name, .email.domain.sld)
+      )
+    )
+    or (
+      // accounts for BCC'd messages where the recipients are empty
+      // if BCC, sometimes the recipient will be the attacker's email
+      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
+      and strings.icontains(sender.display_name, mailbox.email.domain.sld)
+    )
+  )
+
+  and (
+      // at least 1 link or non-image attachment
+      (
+        length(body.links) > 0
+        // these attacks all use compromosed senders, so we look for a domain
+        // that doesn't match the sender's domain to weed out legit messages
+        and any(body.links, .href_url.domain.root_domain != sender.email.domain.root_domain)
+      )
+      or length(filter(attachments, .file_type not in $file_types_images)) > 0
+  )
+
+  and not (
+    strings.contains(sender.display_name, "on behalf of")
+    and sender.email.domain.root_domain == "microsoftonline.com"
+  )
+
+  and all(recipients.to, .email.email != sender.email.email)
+
+  // negate highly trusted sender domains unless they fail DMARC authentication
+  and (
+    (
+      sender.email.domain.root_domain in $high_trust_sender_root_domains
+      and (
+        any(distinct(headers.hops, .authentication_results.dmarc is not null),
+            strings.ilike(.authentication_results.dmarc, "*fail")
+        )
+      )
+    )
+    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
+  )
+  and (
+    (
+      profile.by_sender().prevalence in ("new", "outlier")
+      and not profile.by_sender().solicited
+    )
+    or (
+      profile.by_sender().any_messages_malicious_or_spam
+      and not profile.by_sender().any_false_positives
+    )
+  )
+  and not profile.by_sender().any_false_positives
+attack_types:
+  - "Credential Phishing"
+tactics_and_techniques:
+  - "Social engineering"
+detection_methods:
+  - "Header analysis"
+  - "Sender analysis"
+id: "81a8ed12-0e26-5998-90ae-03334f358704"

detection-rules/impersonation_recipient_domain_display_name_subject.yml

@@ -0,0 +1,79 @@
+name: "Display name and subject impersonation using recipient SLD (new sender)"
+description: |
+  The recipient domain's SLD is used in the sender's display name
+  and in the subject to impersonate the organization. 
+type: "rule"
+severity: "medium"
+source: |
+  type.inbound
+  and (
+    // recipient SLD is being impersonated in the subject + display name
+    (
+       // these are usually targeted with just 1 recipient,
+      // but sometimes they CC themselves or have a blank CC
+      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
+      and any(recipients.to,
+              // ensure that we're checking the org SLD
+              .email.domain.sld in $org_slds
+              and strings.icontains(subject.subject, .email.domain.sld)
+              and strings.icontains(sender.display_name, .email.domain.sld)
+      )
+    )
+    or (
+      // accounts for BCC'd messages where the recipients are empty
+      // if BCC, sometimes the recipient will be the attacker's email
+      length(recipients.to) + length(recipients.cc) + length(recipients.bcc) <= 2
+      and strings.icontains(subject.subject, mailbox.email.domain.sld)
+      and strings.icontains(sender.display_name, mailbox.email.domain.sld)
+    )
+  )
+
+  and (
+      // at least 1 link or non-image attachment
+      (
+        length(body.links) > 0
+        // these attacks all use compromosed senders, so we look for a domain
+        // that doesn't match the sender's domain to weed out legit messages
+        and any(body.links, .href_url.domain.root_domain != sender.email.domain.root_domain)
+      )
+      or length(filter(attachments, .file_type not in $file_types_images)) > 0
+  )
+
+  and not (
+    strings.contains(sender.display_name, "on behalf of")
+    and sender.email.domain.root_domain == "microsoftonline.com"
+  )
+
+  and all(recipients.to, .email.email != sender.email.email)
+
+  // negate highly trusted sender domains unless they fail DMARC authentication
+  and (
+    (
+      sender.email.domain.root_domain in $high_trust_sender_root_domains
+      and (
+        any(distinct(headers.hops, .authentication_results.dmarc is not null),
+            strings.ilike(.authentication_results.dmarc, "*fail")
+        )
+      )
+    )
+    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
+  )
+  and (
+    (
+      profile.by_sender().prevalence in ("new", "outlier")
+      and not profile.by_sender().solicited
+    )
+    or (
+      profile.by_sender().any_messages_malicious_or_spam
+      and not profile.by_sender().any_false_positives
+    )
+  )
+  and not profile.by_sender().any_false_positives
+attack_types:
+  - "Credential Phishing"
+tactics_and_techniques:
+  - "Social engineering"
+detection_methods:
+  - "Header analysis"
+  - "Sender analysis"
+id: "cb2b3ed3-268f-5753-9d2b-194d2ee1ed2e"

detection-rules/impersonation_twitter.yml

@@ -12,7 +12,7 @@ source: |
     or strings.ilevenshtein(sender.display_name, 'twitter') <= 1
     or strings.ilike(sender.email.domain.domain, '*twitter*')
   )
-  and sender.email.domain.domain not in~ ('twitter.com', 'privaterelay.appleid.com', 'stripe.com', 'x.com')
+  and sender.email.domain.domain not in~ ('twitter.com', 'privaterelay.appleid.com', 'stripe.com', 'x.com', 'twitter.discoursemail.com')
   and sender.email.email not in $recipient_emails
 attack_types:
   - "Credential Phishing"

detection-rules/link_credential_phishing_intent_and_other_indicators.yml

@@ -331,6 +331,18 @@ source: |
       and not profile.by_sender().any_false_positives
     )
   )
+  // negate highly trusted sender domains unless they fail DMARC authentication
+  and (
+    (
+      sender.email.domain.root_domain in $high_trust_sender_root_domains
+      and (
+        any(distinct(headers.hops, .authentication_results.dmarc is not null),
+            strings.ilike(.authentication_results.dmarc, "*fail")
+        )
+      )
+    )
+    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
+  )
 attack_types:
   - "Credential Phishing"
 tactics_and_techniques:

detection-rules/link_deactivated_bitly.yml

@@ -11,7 +11,7 @@ source: |
           // link doesn't forward through
           and beta.linkanalysis(.).effective_url.domain.domain == "bit.ly"
           // blocked or gated by bit.ly
-          and strings.ilike(beta.linkanalysis(.).final_dom.display_text, "*link*blocked*", "*flagged*by*", "*been*deactivated*")
+          and strings.ilike(beta.linkanalysis(.).final_dom.display_text, "*link*blocked*", "*flagged*by*")
   )
 attack_types:
   - "Credential Phishing"

detection-rules/qr_code_suspicious_indicators.yml

@@ -15,33 +15,44 @@ source: |
                   // exclude images taken with mobile cameras and screenshots from android
                   and not any(.scan.exiftool.fields,
                               .key == "Model"
-                              or .key == "Software" and strings.starts_with(.value, "Android")
+                              or .key == "Software"
+                              and strings.starts_with(.value, "Android")
                   )
                   // exclude images taken with mobile cameras and screenshots from Apple
                   and not any(.scan.exiftool.fields,
-                              .key == "DeviceManufacturer" and .value == "Apple Computer Inc."
+                              .key == "DeviceManufacturer"
+                              and .value == "Apple Computer Inc."
                   )
           )
       )
       or (
         length(attachments) == 0
-        and any(file.explode(beta.message_screenshot()), .scan.qr.type is not null)
+        and any(file.explode(beta.message_screenshot()),
+                .scan.qr.type is not null and regex.contains(.scan.qr.data, '\.')
+        )
       )
     )
     and (
-      any(recipients.to, strings.icontains(sender.display_name, .email.domain.sld))
+      any(recipients.to,
+          strings.icontains(sender.display_name, .email.domain.sld)
+      )
       or length(body.current_thread.text) is null
       or body.current_thread.text == ""
       or regex.contains(subject.subject,
                         "(Authenticat(e|or|ion)|2fa|Multi.Factor|(qr|bar).code|action.require|alert|Att(n|ention):)"
       )
       or (any(recipients.to, strings.icontains(subject.subject, .display_name)))
       or (
-        (length(recipients.to) == 0 or all(recipients.to, .display_name == "Undisclosed recipients"))
+        (
+          length(recipients.to) == 0
+          or all(recipients.to, .display_name == "Undisclosed recipients")
+        )
         and length(recipients.cc) == 0
         and length(recipients.bcc) == 0
       )
-      or any(file.explode(beta.message_screenshot()), (.scan.qr.url.domain.tld in $suspicious_tlds))
+      or any(file.explode(beta.message_screenshot()),
+             (.scan.qr.url.domain.tld in $suspicious_tlds)
+      )
       or any(attachments,
              .file_type in $file_types_images
              and any(file.explode(.), .scan.qr.url.domain.tld in $suspicious_tlds)