sublimehighRule

Attachment: ICS file with meeting prefix

Detects incoming messages with a single ICS calendar file attachment that has a filename starting with 'meeting_'.

MITRE ATT&CK

T1566.002 T1534 T1656 T1566 T1566.001 T1598

initial-access

Detection Query

type.inbound
and length(attachments) == 1
and any(filter(attachments,
               .file_extension in~ ('ics')
               or .content_type in ("application/ics", "text/calendar")
        ),
        regex.icontains(.file_name, 'meeting_[a-zA-Z0-9]{5}\.')
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Attachment: ICS file with meeting prefix"
description: "Detects incoming messages with a single ICS calendar file attachment that has a filename starting with 'meeting_'."
type: "rule"
severity: "high"
source: |
  type.inbound
  and length(attachments) == 1
  and any(filter(attachments,
                 .file_extension in~ ('ics')
                 or .content_type in ("application/ics", "text/calendar")
          ),
          regex.icontains(.file_name, 'meeting_[a-zA-Z0-9]{5}\.')
  )
attack_types:
  - "BEC/Fraud"
  - "Credential Phishing"
tactics_and_techniques:
  - "Social engineering"
detection_methods:
  - "File analysis"
  - "Header analysis"
id: "383a5810-0b85-55a8-ac9b-e7135823317b"