Detection Method: Header analysis

Header analysis inspects the metadata in message headers to find suspicious patterns, anomalies, or inconsistencies that could indicate phishing, spoofing, or other types of malicious activity. It looks at various header fields like routing information, authentication results, and sender verification data to help spot potential threats.
This includes sender authentication headers like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) results to verify the sender's legitimacy. It also checks how the email traveled through mail servers, looking for any unusual routing that might suggest tampering.
Header analysis can detect:
  • Email spoofing, where attackers forge the sender’s address to appear legitimate
  • Mismatched or inconsistent sender details
  • Suspicious return paths that don’t match the expected sender
  • Unusual routing patterns that stand out from normal email flow
  • Authentication failures that signal potential impersonation attempts
For example, attackers might try to forge email headers to make phishing emails appear as if they’re coming from a trusted source like your bank or your company’s internal email. Header analysis helps you catch these attempts by identifying mismatches between the displayed sender and the actual sending server.
Rule Name & Severity
Last Updated
Author
Types, Tactics & Capabilities
Brand Impersonation: PayPal
4d ago
Feb 13th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-paypal-a6b2ceee
Brand impersonation: Amazon
4d ago
Feb 13th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-amazon-13fc967d
Russia return-path TLD (untrusted sender)
4d ago
Feb 13th, 2026
Sublime Security
/feeds/core/detection-rules/russia-return-path-tld-untrusted-sender-588b3954
Credential phishing: Tax form impersonation with payment request
4d ago
Feb 13th, 2026
Sublime Security
/feeds/core/detection-rules/credential-phishing-tax-form-impersonation-with-payment-request-717695cf
Brand impersonation: Dropbox
5d ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-dropbox-61f11d12
Brand impersonation: TikTok
5d ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-tiktok-aaacc8b7
Link: PDF filename impersonation with credential theft language
5d ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/link-pdf-filename-impersonation-with-credential-theft-language-05931513
Callback Phishing via Zoom comment
6d ago
Feb 11th, 2026
Sublime Security
/feeds/core/detection-rules/callback-phishing-via-zoom-comment-8ec30881
PayPal invoice abuse
6d ago
Feb 11th, 2026
Sublime Security
/feeds/core/detection-rules/paypal-invoice-abuse-0ff7a0d4
Reconnaissance: Empty subject with mismatched reply-to from new sender
11d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/reconnaissance-empty-subject-with-mismatched-reply-to-from-new-sender-12f4bd45
Brand Impersonation: Disney
11d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-disney-bf90b8fb
Brand impersonation: Microsoft Teams invitation
11d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-microsoft-teams-invitation-46410ad8
Brand impersonation: Microsoft Planner with suspicious link
11d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-microsoft-planner-with-suspicious-link-ea363c08
Reconnaissance: All recipients cc/bcc'd or undisclosed
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/reconnaissance-all-recipients-ccbccd-or-undisclosed-420f60d3
Brand impersonation: DocuSign
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-docusign-4d29235c
ClickFunnels link infrastructure abuse
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/clickfunnels-link-infrastructure-abuse-9192fbe9
Brand impersonation: Meta and subsidiaries
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-meta-and-subsidiaries-e38f1e3b
Attachment: Legal themed message or PDF with suspicious indicators
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/attachment-legal-themed-message-or-pdf-with-suspicious-indicators-19133301
macOS malware: Compiled AppleScript with document double-extension
12d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/macos-malware-compiled-applescript-with-document-double-extension-9669c169
Brand impersonation: Netflix
14d ago
Feb 3rd, 2026
min0k
/feeds/core/detection-rules/brand-impersonation-netflix-9f39eea5