Detection rules › Sublime MQL
Attachment: HTML file with excessive padding and suspicious patterns
Attached HTML file contains excessive line breaks and suspicious Javascript patterns.
Threat classification
Sublime's own taxonomy (not MITRE ATT&CK).
| Category | Values |
|---|---|
| Attack types | Credential Phishing, Malware/Ransomware |
| Tactics and techniques | Evasion, HTML smuggling |
Event coverage
| Message attribute |
|---|
| attachments (collection) |
| type |
Rule body MQL
type.inbound
and any(attachments,
(
.content_type == "text/html"
or .file_extension in~ ("html", "htm", "shtml", "dhtml")
or .file_type == "html"
)
and any(file.explode(.),
any(.scan.yara.matches, .name == "HTML_EXCESSIVE_PADDING")
)
)
Detection logic
Scope: inbound message.
Attached HTML file contains excessive line breaks and suspicious Javascript patterns.
- inbound message
any of
attachmentswhere all hold:any of:
- .content_type is 'text/html'
- .file_extension in ('html', 'htm', 'shtml', 'dhtml')
- .file_type is 'html'
any of
file.explode(.)where:any of
.scan.yara.matcheswhere:- .name is 'HTML_EXCESSIVE_PADDING'
Inspects: attachments[].content_type, attachments[].file_extension, attachments[].file_type, type.inbound. Sensors: file.explode.
Indicators matched (7)
| Field | Match | Value |
|---|---|---|
attachments[].content_type | equals | text/html |
attachments[].file_extension | member | html |
attachments[].file_extension | member | htm |
attachments[].file_extension | member | shtml |
attachments[].file_extension | member | dhtml |
attachments[].file_type | equals | html |
file.explode(attachments[])[].scan.yara.matches[].name | equals | HTML_EXCESSIVE_PADDING |