Detection rules › Sublime MQL
Attachment: HTML smuggling with raw array buffer
Recursively scans files and archives to detect HTML smuggling techniques.
Threat classification
Sublime's own taxonomy (not MITRE ATT&CK).
| Category | Values |
|---|---|
| Attack types | Credential Phishing, Malware/Ransomware |
| Tactics and techniques | Evasion, Free subdomain host, HTML smuggling |
Event coverage
| Message attribute |
|---|
| attachments (collection) |
| type |
Rule body MQL
type.inbound
and any(attachments,
(
.file_extension in~ ("html", "htm", "shtml", "dhtml")
or .file_extension in~ $file_extensions_common_archives
or .file_type == "html"
)
and any(file.explode(.),
any(.scan.strings.strings,
// arrayBuffer, eg repetition:
// [0xa0,0x8e,0xd0,0x60,...]
regex.icontains(., '(\W?0x[a-zA-Z0-9]{2}\W?,\s*){100}')
)
and any(.scan.strings.strings, strings.contains(., ".map"))
)
)
Detection logic
Scope: inbound message.
Recursively scans files and archives to detect HTML smuggling techniques.
- inbound message
any of
attachmentswhere all hold:any of:
- .file_extension in ('html', 'htm', 'shtml', 'dhtml')
- .file_extension in $file_extensions_common_archives
- .file_type is 'html'
any of
file.explode(.)where all hold:any of
.scan.strings.stringswhere:- . matches '(\\W?0x[a-zA-Z0-9]{2}\\W?,\\s*){100}'
any of
.scan.strings.stringswhere:- . contains '.map'
Inspects: attachments[].file_extension, attachments[].file_type, type.inbound. Sensors: file.explode, regex.icontains, strings.contains. Reference lists: $file_extensions_common_archives.
Indicators matched (7)
| Field | Match | Value |
|---|---|---|
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 |
regex.icontains | regex | (\W?0x[a-zA-Z0-9]{2}\W?,\s*){100} |
strings.contains | substring | .map |