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: Dropbox
6h ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-dropbox-61f11d12
Brand impersonation: TikTok
6h ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-tiktok-aaacc8b7
Link: PDF filename impersonation with credential theft language
6h ago
Feb 12th, 2026
Sublime Security
/feeds/core/detection-rules/link-pdf-filename-impersonation-with-credential-theft-language-05931513
Callback Phishing via Zoom comment
1d ago
Feb 11th, 2026
Sublime Security
/feeds/core/detection-rules/callback-phishing-via-zoom-comment-8ec30881
PayPal invoice abuse
1d ago
Feb 11th, 2026
Sublime Security
/feeds/core/detection-rules/paypal-invoice-abuse-0ff7a0d4
Reconnaissance: Empty subject with mismatched reply-to from new sender
6d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/reconnaissance-empty-subject-with-mismatched-reply-to-from-new-sender-12f4bd45
Brand Impersonation: Disney
6d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-disney-bf90b8fb
Brand impersonation: Microsoft Teams invitation
6d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-microsoft-teams-invitation-46410ad8
Brand impersonation: Microsoft Planner with suspicious link
6d ago
Feb 6th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-microsoft-planner-with-suspicious-link-ea363c08
Brand impersonation: DocuSign
7d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-docusign-4d29235c
Reconnaissance: All recipients cc/bcc'd or undisclosed
7d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/reconnaissance-all-recipients-ccbccd-or-undisclosed-420f60d3
Brand impersonation: Meta and subsidiaries
7d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-meta-and-subsidiaries-e38f1e3b
ClickFunnels link infrastructure abuse
7d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/clickfunnels-link-infrastructure-abuse-9192fbe9
Attachment: Legal themed message or PDF with suspicious indicators
7d 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
7d ago
Feb 5th, 2026
Sublime Security
/feeds/core/detection-rules/macos-malware-compiled-applescript-with-document-double-extension-9669c169
Brand impersonation: Netflix
9d ago
Feb 3rd, 2026
min0k
/feeds/core/detection-rules/brand-impersonation-netflix-9f39eea5
Service abuse: Trello board invitation with VIP impersonation
9d ago
Feb 3rd, 2026
Sublime Security
/feeds/core/detection-rules/service-abuse-trello-board-invitation-with-vip-impersonation-fedfc94b
Brand impersonation: Marriott with gift language
10d ago
Feb 2nd, 2026
Sublime Security
/feeds/core/detection-rules/brand-impersonation-marriott-with-gift-language-39b32b97
Impersonation: Executive using numbered local part
13d ago
Jan 30th, 2026
Sublime Security
/feeds/core/detection-rules/impersonation-executive-using-numbered-local-part-8e005a22
VIP impersonation with w2 request
14d ago
Jan 29th, 2026
Sublime Security
/feeds/core/detection-rules/vip-impersonation-with-w2-request-e7e73fad