Detection rules › Sublime MQL
Attachment: Macro with suspected use of COM ShellBrowserWindow object for process creation
Macro references the ShellBrowserWindow COM object which can be used to spawn new processes from Explorer.exe rather than as a child process of the Office application. This can be useful for a threat actor attempting to evade security controls.
Threat classification
Sublime's own taxonomy (not MITRE ATT&CK).
| Category | Values |
|---|---|
| Attack types | Malware/Ransomware |
| Tactics and techniques | Macros, Scripting |
Event coverage
| Message attribute |
|---|
| attachments (collection) |
| type |
Rule body MQL
type.inbound
and any(attachments,
(
.file_extension in~ $file_extensions_macros
or (
.file_extension is null
and .file_type == "unknown"
and .content_type == "application/octet-stream"
and .size < 100000000
)
)
and any(file.explode(.),
any(.scan.strings.strings,
strings.ilike(.,
"*new:C08AFD90-F2A1-11D1-8455-00A0C91F3880*"
)
)
)
)
Detection logic
Scope: inbound message.
Macro references the ShellBrowserWindow COM object which can be used to spawn new processes from Explorer.exe rather than as a child process of the Office application. This can be useful for a threat actor attempting to evade security controls.
- inbound message
any of
attachmentswhere all hold:any of:
- .file_extension in $file_extensions_macros
all of:
- .file_extension is missing
- .file_type is 'unknown'
- .content_type is 'application/octet-stream'
- .size < 100000000
any of
file.explode(.)where:any of
.scan.strings.stringswhere:- . matches '*new:C08AFD90-F2A1-11D1-8455-00A0C91F3880*'
Inspects: attachments[].content_type, attachments[].file_extension, attachments[].file_type, attachments[].size, type.inbound. Sensors: file.explode, strings.ilike. Reference lists: $file_extensions_macros.
Indicators matched (3)
| Field | Match | Value |
|---|---|---|
attachments[].file_type | equals | unknown |
attachments[].content_type | equals | application/octet-stream |
strings.ilike | substring | *new:C08AFD90-F2A1-11D1-8455-00A0C91F3880* |