Detection rules › Sublime MQL

Attachment: ICS file with AWS Lambda URL

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

Detects ICS calendar files that contain references to AWS Lambda URLs, which may be used to deliver malicious content or redirect users to suspicious resources.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesEvasion, Free file host, ICS Phishing

Event coverage

Rule body MQL

type.inbound
and any(attachments,
        (
          .file_extension in~ ('ics')
          or .content_type in ("application/ics", "text/calendar")
        )
        and regex.icontains(file.parse_text(.).text, 'lambda-url')
)

Detection logic

Scope: inbound message.

Detects ICS calendar files that contain references to AWS Lambda URLs, which may be used to deliver malicious content or redirect users to suspicious resources.

  1. inbound message
  2. any of attachments where all hold:
    • any of:
      • .file_extension in ('ics')
      • .content_type in ('application/ics', 'text/calendar')
    • file.parse_text(.).text matches 'lambda-url'

Inspects: attachments[].content_type, attachments[].file_extension, type.inbound. Sensors: file.parse_text, regex.icontains.

Indicators matched (4)

FieldMatchValue
attachments[].file_extensionmemberics
attachments[].content_typememberapplication/ics
attachments[].content_typemembertext/calendar
regex.icontainsregexlambda-url