Merge branch 'main' into sam.html.javascript

detection-rules/attachment_html_smuggling_body_onload.yml

@@ -0,0 +1,49 @@
+name: "Attachment: HTML smuggling 'body onload' linking to suspicious destination"
+description: |
+  Potential HTML Smuggling. 
+  This rule inspects HTML attachments that contain a single link and leveraging an HTML body onload event. The linked domain must be in the URLhaus trusted repoters list, or have a suspicious TLD. 
+type: "rule"
+severity: "high"
+source: |
+  type.inbound
+  and any(attachments,
+          (
+            .file_extension in~ ("html", "htm", "shtml", "dhtml", "xhtml")
+            or (
+              .file_extension is null
+              and .file_type == "unknown"
+              and .content_type == "application/octet-stream"
+            )
+            or .file_extension in~ $file_extensions_common_archives
+            or .file_type == "html"
+            or .content_type == "text/html"
+          )
+          and any(file.explode(.),
+                  not length(.scan.url.invalid_urls) > 0
+                  and length(.scan.url.urls) == 1
+                  and any(.scan.strings.strings, strings.ilike(., "*body onload*"))
+                  and (
+                    any(.scan.url.urls,
+                        .domain.root_domain in $abuse_ch_urlhaus_domains_trusted_reporters
+                        
+                        // To-do uncomment below when list is created
+                        //or .domain.root_domain in $suspicious_root_domains
+                        or .domain.tld in $suspicious_tlds
+                    )
+                  )
+          )
+  )
+attack_types:
+  - "Credential Phishing"
+  - "Malware/Ransomware"
+tactics_and_techniques:
+  - "Evasion"
+  - "HTML smuggling"
+  - "Scripting"
+detection_methods:
+  - "Archive analysis"
+  - "Content analysis"
+  - "File analysis"
+  - "HTML analysis"
+  - "Link analysis"
+id: "c1e2beed-e71e-58d2-b922-9601337645b2"

detection-rules/attachment_html_smuggling_decimal_encoding.yml

@@ -0,0 +1,39 @@
+name: "Attachment: HTML smuggling with decimal encoding"
+description: |
+  Potential HTML smuggling attack based on large blocks of decimal encoding. Attackers often use decimal encoding as an obfuscation technique to bypass traditional email security measures. 
+type: "rule"
+severity: "high"
+source: |
+  type.inbound
+  and any(attachments,
+          (
+            .file_extension in~ ("html", "htm", "shtml", "dhtml", "xhtml")
+            or (
+              .file_extension is null
+              and .file_type == "unknown"
+              and .content_type == "application/octet-stream"
+            )
+            or .file_extension in~ $file_extensions_common_archives
+            or .file_type == "html"
+            or .content_type == "text/html"
+          )
+          and any(file.explode(.),
+                  // suspicious identifiers
+                  any(.scan.strings.strings,
+                      regex.contains(., '(\d{2,3},){60,}')
+                  )
+          )
+  )
+attack_types:
+  - "Credential Phishing"
+  - "Malware/Ransomware"
+tactics_and_techniques:
+  - "Evasion"
+  - "HTML smuggling"
+  - "Scripting"
+detection_methods:
+  - "Archive analysis"
+  - "Content analysis"
+  - "File analysis"
+  - "HTML analysis"
+id: "f99213c4-7031-50b1-ae81-b45f790d3fa4"

detection-rules/body_business_email_compromise_unsolicited.yml

@@ -27,7 +27,22 @@ source: |
       )
     ),
   )
-
+  
+  // negate "via" senders via dmarc authentication or gmail autoforwards
+  and (
+    not (
+      any(distinct(headers.hops, .authentication_results.dmarc is not null),
+          strings.ilike(.authentication_results.dmarc, "pass")
+          or (
+            not any([headers.return_path.email],
+                    strings.ilike(headers.return_path.local_part, "*+caf_=*")
+            )
+            and strings.contains(sender.display_name, "via")
+          )
+      )
+    )
+  )
+  
   // unsolicited
   and (
     (
@@ -39,6 +54,7 @@ source: |
       and sender.email.domain.domain not in $recipient_domains
     )
   )
+
 attack_types:
   - "BEC/Fraud"
 tactics_and_techniques: