Sublime Security

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HTML analysis
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Attack Types
BEC/Fraud
Callback Phishing
Credential Phishing
Extortion
Malware/Ransomware
Reconnaissance
Spam
Tactics and Techniques
Encryption
Evasion
Exploit
Free email provider
Free file host
Free subdomain host
HTML smuggling
Image as content
Impersonation: Brand
Impersonation: Employee
Impersonation: VIP
IPFS
ISO
LNK
Lookalike domain
Macros
OneNote
Open redirect
Out of band pivot
PDF
Punycode
QR code
Scripting
Social engineering
Spoofing
Detection Methods
Archive analysis
Content analysis
Computer Vision
Exif analysis
File analysis
Header analysis
HTML analysis
Javascript analysis
Macro analysis
Natural Language Understanding
Optical Character Recognition
OLE analysis
PDF analysis
QR code analysis
Sender analysis
Threat intelligence
URL analysis
URL screenshot
Whois
XML analysis
YARA
Detection Method: HTML analysis
HTML analysis looks at the HTML code in emails, web pages, or attachments to spot potentially malicious elements or deceptive structures. It examines both what’s visible and hidden in the HTML to uncover tactics often used in phishing or malware attacks.
HTML analysis can help you detect:
Hidden scripts or iframes that might run harmful code
Obfuscated JavaScript designed to avoid detection
Misleading hyperlinks where the displayed text doesn’t match the real URL
Forms made to steal credentials or sensitive data
Suspicious HTML comments with hidden instructions
CSS tricks used to hide malicious content
For example, phishing emails often use HTML to replicate trusted login pages. HTML analysis can catch the hidden forms and scripts trying to steal your credentials.
Blog Posts
Talking phish over turkey · Blog · Sublime Security
Living Off the Land: Credential Phishing via Docusign abuse · Blog · Sublime Security
Call Me Maybe? The Rise of Callback Phishing Emails · Blog · Sublime Security
Attack Types (6):
Credential Phishing
Spam
Malware/Ransomware
BEC/Fraud
Callback Phishing
Extortion
Tactics & Techniques (21):
Impersonation: Brand
Social engineering
Evasion
Free subdomain host
Credential Phishing
HTML smuggling
Scripting
Exploit
Encryption
Impersonation: Employee
Lookalike domain
OneNote
PDF
Impersonation: VIP
Free file host
Open redirect
Free email provider
Image as content
HTML injection
Out of band pivot
ISO
Rule Name & Severity
Last Updated
Types, Tactics & Capabilities
Brand impersonation: File sharing notification with template artifacts
16m ago
Jan 23rd, 2026
Sublime Security
Credential Phishing
Impersonation: Brand
Social engineering
Evasion
HTML analysis
Computer Vision
Content analysis
Header analysis
Credential Phishing
Impersonation: Brand
Social engineering
Evasion
HTML analysis
Computer Vision
Content analysis
Header analysis
/feeds/core/detection-rules/brand-impersonation-file-sharing-notification-with-template-artifacts-37d89611
Link: Tycoon2FA phishing kit (non-exhaustive)
12h ago
Jan 23rd, 2026
Sublime Security
Credential Phishing
Free subdomain host
Evasion
Credential Phishing
URL analysis
HTML analysis
Content analysis
Credential Phishing
Free subdomain host
Evasion
Credential Phishing
URL analysis
HTML analysis
Content analysis
/feeds/core/detection-rules/link-tycoon2fa-phishing-kit-non-exhaustive-a070d4e2
Spam: Commonly observed formatting of unauthorized free giveaways
9d ago
Jan 14th, 2026
Sublime Security
Spam
Impersonation: Brand
Social engineering
Content analysis
HTML analysis
Sender analysis
URL analysis
Spam
Impersonation: Brand
Social engineering
Content analysis
HTML analysis
Sender analysis
URL analysis
/feeds/core/detection-rules/spam-commonly-observed-formatting-of-unauthorized-free-giveaways-8bc49fa3
Link: Common hidden directory observed
10d ago
Jan 13th, 2026
Sublime Security
Credential Phishing
Evasion
URL analysis
HTML analysis
Credential Phishing
Evasion
URL analysis
HTML analysis
/feeds/core/detection-rules/link-common-hidden-directory-observed-9f316da6
Service abuse: Random Google Firebase sender address with suspicious content
11d ago
Jan 12th, 2026
Sublime Security
Spam
Credential Phishing
Free subdomain host
Social engineering
Content analysis
Header analysis
HTML analysis
Natural Language Understanding
Sender analysis
URL analysis
Whois
Spam
Credential Phishing
Free subdomain host
Social engineering
Content analysis
Header analysis
HTML analysis
Natural Language Understanding
Sender analysis
URL analysis
Whois
/feeds/core/detection-rules/service-abuse-random-google-firebase-sender-address-with-suspicious-content-9f8899a9
Attachment: HTML smuggling with eval and atob via calendar invite
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
Scripting
File analysis
HTML analysis
Javascript analysis
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
Scripting
File analysis
HTML analysis
Javascript analysis
/feeds/core/detection-rules/attachment-html-smuggling-with-eval-and-atob-via-calendar-invite-597c2edd
Attachment: HTML smuggling with atob and high entropy via calendar invite
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
Scripting
File analysis
HTML analysis
Javascript analysis
Sender analysis
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
Scripting
File analysis
HTML analysis
Javascript analysis
Sender analysis
/feeds/core/detection-rules/attachment-html-smuggling-with-atob-and-high-entropy-via-calendar-invite-94d84614
CVE-2023-5631 - Roundcube Webmail XSS via crafted SVG
11d ago
Jan 12th, 2026
Sublime Security
Malware/Ransomware
Evasion
Exploit
HTML smuggling
Scripting
Content analysis
HTML analysis
Sender analysis
Malware/Ransomware
Evasion
Exploit
HTML smuggling
Scripting
Content analysis
HTML analysis
Sender analysis
/feeds/core/detection-rules/cve-2023-5631-roundcube-webmail-xss-via-crafted-svg-8405d61b
URI protocol handler: search-ms
11d ago
Jan 12th, 2026
Sublime Security
Malware/Ransomware
Evasion
File analysis
HTML analysis
Malware/Ransomware
Evasion
File analysis
HTML analysis
/feeds/core/detection-rules/uri-protocol-handler-search-ms-ee27d9c0
Attachment: EML file contains HTML attachment with login portal indicators
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Evasion
HTML smuggling
Content analysis
File analysis
Header analysis
HTML analysis
Javascript analysis
Sender analysis
Credential Phishing
Evasion
HTML smuggling
Content analysis
File analysis
Header analysis
HTML analysis
Javascript analysis
Sender analysis
/feeds/core/detection-rules/attachment-eml-file-contains-html-attachment-with-login-portal-indicators-6e4df158
Attachment: HTML smuggling with ROT13
11d ago
Jan 12th, 2026
@Kyle_Parrish_
Credential Phishing
Malware/Ransomware
Encryption
Evasion
HTML smuggling
Scripting
Archive analysis
Content analysis
File analysis
Javascript analysis
HTML analysis
Credential Phishing
Malware/Ransomware
Encryption
Evasion
HTML smuggling
Scripting
Archive analysis
Content analysis
File analysis
Javascript analysis
HTML analysis
/feeds/core/detection-rules/attachment-html-smuggling-with-rot13-6eacc4cf
Sharepoint link likely unrelated to sender
11d ago
Jan 12th, 2026
Sublime Security
BEC/Fraud
Credential Phishing
Impersonation: Employee
Lookalike domain
OneNote
PDF
Social engineering
URL analysis
Sender analysis
Header analysis
HTML analysis
BEC/Fraud
Credential Phishing
Impersonation: Employee
Lookalike domain
OneNote
PDF
Social engineering
URL analysis
Sender analysis
Header analysis
HTML analysis
/feeds/core/detection-rules/sharepoint-link-likely-unrelated-to-sender-6870f489
Service abuse: Trello board invitation with VIP impersonation
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Impersonation: VIP
Social engineering
Content analysis
Header analysis
HTML analysis
Sender analysis
Credential Phishing
Impersonation: VIP
Social engineering
Content analysis
Header analysis
HTML analysis
Sender analysis
/feeds/core/detection-rules/service-abuse-trello-board-invitation-with-vip-impersonation-fedfc94b
Request for Quote or Purchase (RFQ|RFP) with HTML smuggling attachment
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Evasion
Content analysis
File analysis
HTML analysis
Javascript analysis
Natural Language Understanding
URL analysis
Credential Phishing
Evasion
Content analysis
File analysis
HTML analysis
Javascript analysis
Natural Language Understanding
URL analysis
/feeds/core/detection-rules/request-for-quote-or-purchase-rfqorrfp-with-html-smuggling-attachment-a47a5755
Zoom Events newsletter abuse
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Free file host
Free subdomain host
Social engineering
Impersonation: Brand
Header analysis
HTML analysis
Natural Language Understanding
URL analysis
Credential Phishing
Free file host
Free subdomain host
Social engineering
Impersonation: Brand
Header analysis
HTML analysis
Natural Language Understanding
URL analysis
/feeds/core/detection-rules/zoom-events-newsletter-abuse-c8fce846
Low reputation link to auto-downloaded HTML file with smuggling indicators
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Evasion
Free file host
Free subdomain host
HTML smuggling
Impersonation: Brand
Open redirect
Social engineering
Content analysis
File analysis
HTML analysis
Javascript analysis
Sender analysis
URL analysis
Credential Phishing
Evasion
Free file host
Free subdomain host
HTML smuggling
Impersonation: Brand
Open redirect
Social engineering
Content analysis
File analysis
HTML analysis
Javascript analysis
Sender analysis
URL analysis
/feeds/core/detection-rules/low-reputation-link-to-auto-downloaded-html-file-with-smuggling-indicators-339676c6
Credential phishing: Suspicious e-sign agreement document notification
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Social engineering
Content analysis
Header analysis
HTML analysis
URL analysis
Sender analysis
Credential Phishing
Social engineering
Content analysis
Header analysis
HTML analysis
URL analysis
Sender analysis
/feeds/core/detection-rules/credential-phishing-suspicious-e-sign-agreement-document-notification-9b68c2d8
Attachment: EML containing a base64 encoded script
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Evasion
HTML smuggling
Scripting
Social engineering
File analysis
HTML analysis
Sender analysis
Credential Phishing
Evasion
HTML smuggling
Scripting
Social engineering
File analysis
HTML analysis
Sender analysis
/feeds/core/detection-rules/attachment-eml-containing-a-base64-encoded-script-fc3d9445
Attachment: HTML attachment with login portal indicators
11d ago
Jan 12th, 2026
Credential Phishing
HTML smuggling
Scripting
Archive analysis
File analysis
HTML analysis
Javascript analysis
Sender analysis
Credential Phishing
HTML smuggling
Scripting
Archive analysis
File analysis
HTML analysis
Javascript analysis
Sender analysis
/feeds/core/detection-rules/attachment-html-attachment-with-login-portal-indicators-3aabf4a7
Attachment: HTML file with excessive padding and suspicious patterns
11d ago
Jan 12th, 2026
Sublime Security
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
File analysis
HTML analysis
YARA
Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
File analysis
HTML analysis
YARA
/feeds/core/detection-rules/attachment-html-file-with-excessive-padding-and-suspicious-patterns-0a6aee1e
Page 1 of 5

Rule Name & Severity	Last Updated	Author	Types, Tactics & Capabilities
Brand impersonation: File sharing notification with template artifacts	16m ago Jan 23rd, 2026	Sublime Security	Credential Phishing Impersonation: Brand Social engineering Evasion HTML analysis Computer Vision Content analysis Header analysis	/feeds/core/detection-rules/brand-impersonation-file-sharing-notification-with-template-artifacts-37d89611
Link: Tycoon2FA phishing kit (non-exhaustive)	12h ago Jan 23rd, 2026	Sublime Security	Credential Phishing Free subdomain host Evasion Credential Phishing URL analysis HTML analysis Content analysis	/feeds/core/detection-rules/link-tycoon2fa-phishing-kit-non-exhaustive-a070d4e2
Spam: Commonly observed formatting of unauthorized free giveaways	9d ago Jan 14th, 2026	Sublime Security	Spam Impersonation: Brand Social engineering Content analysis HTML analysis Sender analysis URL analysis	/feeds/core/detection-rules/spam-commonly-observed-formatting-of-unauthorized-free-giveaways-8bc49fa3
Link: Common hidden directory observed	10d ago Jan 13th, 2026	Sublime Security	Credential Phishing Evasion URL analysis HTML analysis	/feeds/core/detection-rules/link-common-hidden-directory-observed-9f316da6
Service abuse: Random Google Firebase sender address with suspicious content	11d ago Jan 12th, 2026	Sublime Security	Spam Credential Phishing Free subdomain host Social engineering Content analysis Header analysis HTML analysis Natural Language Understanding Sender analysis URL analysis Whois	/feeds/core/detection-rules/service-abuse-random-google-firebase-sender-address-with-suspicious-content-9f8899a9
Attachment: HTML smuggling with eval and atob via calendar invite	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Malware/Ransomware Evasion HTML smuggling Scripting File analysis HTML analysis Javascript analysis	/feeds/core/detection-rules/attachment-html-smuggling-with-eval-and-atob-via-calendar-invite-597c2edd
Attachment: HTML smuggling with atob and high entropy via calendar invite	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Malware/Ransomware Evasion HTML smuggling Scripting File analysis HTML analysis Javascript analysis Sender analysis	/feeds/core/detection-rules/attachment-html-smuggling-with-atob-and-high-entropy-via-calendar-invite-94d84614
CVE-2023-5631 - Roundcube Webmail XSS via crafted SVG	11d ago Jan 12th, 2026	Sublime Security	Malware/Ransomware Evasion Exploit HTML smuggling Scripting Content analysis HTML analysis Sender analysis	/feeds/core/detection-rules/cve-2023-5631-roundcube-webmail-xss-via-crafted-svg-8405d61b
URI protocol handler: search-ms	11d ago Jan 12th, 2026	Sublime Security	Malware/Ransomware Evasion File analysis HTML analysis	/feeds/core/detection-rules/uri-protocol-handler-search-ms-ee27d9c0
Attachment: EML file contains HTML attachment with login portal indicators	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Evasion HTML smuggling Content analysis File analysis Header analysis HTML analysis Javascript analysis Sender analysis	/feeds/core/detection-rules/attachment-eml-file-contains-html-attachment-with-login-portal-indicators-6e4df158
Attachment: HTML smuggling with ROT13	11d ago Jan 12th, 2026	@Kyle_Parrish_	Credential Phishing Malware/Ransomware Encryption Evasion HTML smuggling Scripting Archive analysis Content analysis File analysis Javascript analysis HTML analysis	/feeds/core/detection-rules/attachment-html-smuggling-with-rot13-6eacc4cf
Sharepoint link likely unrelated to sender	11d ago Jan 12th, 2026	Sublime Security	BEC/Fraud Credential Phishing Impersonation: Employee Lookalike domain OneNote PDF Social engineering URL analysis Sender analysis Header analysis HTML analysis	/feeds/core/detection-rules/sharepoint-link-likely-unrelated-to-sender-6870f489
Service abuse: Trello board invitation with VIP impersonation	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Impersonation: VIP Social engineering Content analysis Header analysis HTML analysis Sender analysis	/feeds/core/detection-rules/service-abuse-trello-board-invitation-with-vip-impersonation-fedfc94b
Request for Quote or Purchase (RFQ\|RFP) with HTML smuggling attachment	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Evasion Content analysis File analysis HTML analysis Javascript analysis Natural Language Understanding URL analysis	/feeds/core/detection-rules/request-for-quote-or-purchase-rfqorrfp-with-html-smuggling-attachment-a47a5755
Zoom Events newsletter abuse	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Free file host Free subdomain host Social engineering Impersonation: Brand Header analysis HTML analysis Natural Language Understanding URL analysis	/feeds/core/detection-rules/zoom-events-newsletter-abuse-c8fce846
Low reputation link to auto-downloaded HTML file with smuggling indicators	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Evasion Free file host Free subdomain host HTML smuggling Impersonation: Brand Open redirect Social engineering Content analysis File analysis HTML analysis Javascript analysis Sender analysis URL analysis	/feeds/core/detection-rules/low-reputation-link-to-auto-downloaded-html-file-with-smuggling-indicators-339676c6
Credential phishing: Suspicious e-sign agreement document notification	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Social engineering Content analysis Header analysis HTML analysis URL analysis Sender analysis	/feeds/core/detection-rules/credential-phishing-suspicious-e-sign-agreement-document-notification-9b68c2d8
Attachment: EML containing a base64 encoded script	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Evasion HTML smuggling Scripting Social engineering File analysis HTML analysis Sender analysis	/feeds/core/detection-rules/attachment-eml-containing-a-base64-encoded-script-fc3d9445
Attachment: HTML attachment with login portal indicators	11d ago Jan 12th, 2026	@ajpc500	Credential Phishing HTML smuggling Scripting Archive analysis File analysis HTML analysis Javascript analysis Sender analysis	/feeds/core/detection-rules/attachment-html-attachment-with-login-portal-indicators-3aabf4a7
Attachment: HTML file with excessive padding and suspicious patterns	11d ago Jan 12th, 2026	Sublime Security	Credential Phishing Malware/Ransomware Evasion HTML smuggling File analysis HTML analysis YARA	/feeds/core/detection-rules/attachment-html-file-with-excessive-padding-and-suspicious-patterns-0a6aee1e