Detection rules › Sublime MQL
Attachment: ICS calendar file with suspicious product identifier
Detects inbound messages containing ICS calendar attachments that have product identifiers matching patterns commonly associated with malicious calendar invitations. The rule identifies ICS files through multiple detection methods and analyzes the product_id field for suspicious formatting that may indicate automated generation or spoofing attempts.
Threat classification
Sublime's own taxonomy (not MITRE ATT&CK).
| Category | Values |
|---|---|
| Attack types | Credential Phishing |
| Tactics and techniques | Evasion, Social engineering, ICS Phishing |
Event coverage
| Message attribute |
|---|
| attachments (collection) |
| type |
Rule body MQL
type.inbound
and any(attachments,
(
.file_type == "ics"
or .file_extension == "ics"
or .content_type in ("application/ics", "text/calendar")
)
//
// This rule makes use of a beta feature and is subject to change without notice
// using the beta feature in custom rules is not suggested until it has been formally released
//
and regex.icontains(beta.file.parse_ics(.).product_id,
'-//[a-z0-9]*[0-9][a-z0-9]*//EN'
)
)
Detection logic
Scope: inbound message.
Detects inbound messages containing ICS calendar attachments that have product identifiers matching patterns commonly associated with malicious calendar invitations. The rule identifies ICS files through multiple detection methods and analyzes the product_id field for suspicious formatting that may indicate automated generation or spoofing attempts.
- inbound message
any of
attachmentswhere all hold:any of:
- .file_type is 'ics'
- .file_extension is 'ics'
- .content_type in ('application/ics', 'text/calendar')
- beta.file.parse_ics(.).product_id matches '-//[a-z0-9]*[0-9][a-z0-9]*//EN'
Inspects: attachments[].content_type, attachments[].file_extension, attachments[].file_type, type.inbound. Sensors: beta.file.parse_ics, regex.icontains.
Indicators matched (5)
| Field | Match | Value |
|---|---|---|
attachments[].file_type | equals | ics |
attachments[].file_extension | equals | ics |
attachments[].content_type | member | application/ics |
attachments[].content_type | member | text/calendar |
regex.icontains | regex | -//[a-z0-9]*[0-9][a-z0-9]*//EN |