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.
Blog Posts
Credential phishing Charles Schwab account holders with 2FA bypass · Blog · Sublime Security
Credential phishing Charles Schwab account holders with 2FA bypass · Blog · Sublime Security
Hiding a $50,000 BEC financial fraud in a fake email thread · Blog · Sublime Security
Hiding a $50,000 BEC financial fraud in a fake email thread · Blog · Sublime Security
Callback phishing via invoice abuse and distribution list relays · Blog · Sublime Security
Callback phishing via invoice abuse and distribution list relays · Blog · Sublime Security
Detecting malicious AnonymousFox email messages sent from compromised sites · Blog · Sublime Security
Detecting malicious AnonymousFox email messages sent from compromised sites · Blog · Sublime Security
Talking phish over turkey · Blog · Sublime Security
Talking phish over turkey · Blog · Sublime Security
Hidden credential phishing within EML attachments · Blog · Sublime Security
Hidden credential phishing within EML attachments · Blog · Sublime Security
Living Off the Land: Credential Phishing via Docusign abuse · Blog · Sublime Security
Living Off the Land: Credential Phishing via Docusign abuse · Blog · Sublime Security
Living Off the Land: Callback Phishing via Docusign comment · Blog · Sublime Security
Living Off the Land: Callback Phishing via Docusign comment · Blog · Sublime Security
Adversarial ML: Extortion via LLM Manipulation Tactics · Blog · Sublime Security
Adversarial ML: Extortion via LLM Manipulation Tactics · Blog · Sublime Security
QR Code Phishing: Decoding Hidden Threats · Blog · Sublime Security
QR Code Phishing: Decoding Hidden Threats · Blog · Sublime Security
Attack Types (7):
Credential Phishing
Callback Phishing
BEC/Fraud
Malware/Ransomware
Spam
Extortion
Reconnaissance
Tactics & Techniques (24):
Impersonation: Brand
Lookalike domain
Social engineering
Impersonation: Email address
Impersonation: Domain
Evasion
ICS Phishing
Free email provider
Spoofing
Out of band pivot
PDF
Free subdomain host
Open redirect
HTML smuggling
Impersonation: Employee
Impersonation: VIP
Free file host
Image as content
QR code
OneNote
Macros
Exploit
Encryption
Scripting
Rule Name & Severity
Last Updated
Author
Types, Tactics & Capabilities
Brand impersonation: FedEx
2d ago
May 8th, 2026
Sublime Security
Credential Phishing
Impersonation: Brand
Lookalike domain
Social engineering
Header analysis
Sender analysis
Brand impersonation: Quickbooks
2d ago
May 8th, 2026
Sublime Security
Callback Phishing
Credential Phishing
Impersonation: Brand
Social engineering
Computer Vision
Content analysis
Header analysis
Sender analysis
Observed IOC: Malicious sender email addresses
3d ago
May 7th, 2026
Sublime Security
BEC/Fraud
Credential Phishing
Malware/Ransomware
Social engineering
Sender analysis
Header analysis
Observed IOC: Malicious sender domains
3d ago
May 7th, 2026
Sublime Security
BEC/Fraud
Credential Phishing
Malware/Ransomware
Social engineering
Sender analysis
Header analysis
Brand Impersonation: PayPal
3d ago
May 7th, 2026
Sublime Security
Credential Phishing
Impersonation: Brand
Lookalike domain
Social engineering
Computer Vision
Content analysis
File analysis
Header analysis
Sender analysis
Brand impersonation: Booking.com
4d ago
May 6th, 2026
Sublime Security
Credential Phishing
Impersonation: Brand
Social engineering
Natural Language Understanding
Header analysis
Sender analysis
Callback phishing via calendar invite
4d ago
May 6th, 2026
Sublime Security
Callback Phishing
Social engineering
Evasion
ICS Phishing
File analysis
Header analysis
Natural Language Understanding
Sender analysis
Suspicious newly registered reply-to domain with engaging financial or urgent language
4d ago
May 6th, 2026
Sublime Security
BEC/Fraud
Social engineering
Content analysis
Header analysis
Natural Language Understanding
Sender analysis
URL analysis
Whois
Service Abuse: Zoom with freemail reply-to and recipient address in greeting
4d ago
May 6th, 2026
Sublime Security
Spam
Free email provider
Social engineering
Sender analysis
Header analysis
Content analysis
Link: Romance/Sexual Language With Suspicious Link
5d ago
May 5th, 2026
Sublime Security
Spam
Social engineering
Content analysis
Header analysis
URL analysis
Whois
Service abuse: Zoom with newly registered reply-to domain
6d ago
May 4th, 2026
Sublime Security
Spam
Social engineering
Evasion
Sender analysis
Header analysis
Whois
Extortion / sextortion (untrusted sender)
6d ago
May 4th, 2026
Sublime Security
Extortion
Social engineering
Spoofing
Content analysis
Header analysis
Natural Language Understanding
Sender analysis
Callback phishing: SumUp infrastructure abuse
6d ago
May 4th, 2026
Sublime Security
BEC/Fraud
Callback Phishing
Evasion
Social engineering
Content analysis
Header analysis
Sender analysis
Callback phishing via Intuit service abuse
6d ago
May 4th, 2026
Sublime Security
Callback Phishing
Evasion
Free email provider
Impersonation: Brand
Social engineering
Computer Vision
Content analysis
Header analysis
Optical Character Recognition
Impersonation: Suspected supplier impersonation with suspicious content
6d ago
May 4th, 2026
Sublime Security
BEC/Fraud
Evasion
Free email provider
Lookalike domain
Social engineering
Content analysis
Header analysis
Natural Language Understanding
Sender analysis
URL analysis
Whois
Observed IOC: Malicious sender root domains
6d ago
May 4th, 2026
Sublime Security
BEC/Fraud
Credential Phishing
Malware/Ransomware
Social engineering
Sender analysis
Header analysis
Callback phishing via Adobe Sign comment
6d ago
May 4th, 2026
Sublime Security
Callback Phishing
Evasion
Impersonation: Brand
Out of band pivot
Social engineering
Content analysis
Computer Vision
Header analysis
Sender analysis
URL analysis
PayPal invoice abuse
6d ago
May 4th, 2026
Sublime Security
BEC/Fraud
Callback Phishing
Evasion
Social engineering
Content analysis
Header analysis
Sender analysis
Brand impersonation: Trust Wallet
6d ago
May 4th, 2026
Sublime Security
BEC/Fraud
Credential Phishing
Impersonation: Brand
Social engineering
Natural Language Understanding
Sender analysis
Header analysis
Callback phishing: AOL senders with suspicious HTML template or PDF attachment
6d ago
May 4th, 2026
Sublime Security
Callback Phishing
Free email provider
Social engineering
Content analysis
Header analysis
File analysis
HTML analysis
Exif analysis
Sender analysis
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