Medium Severity

Attachment: ICS calendar file with suspicious product identifier

Labels

Credential Phishing

Evasion

Description

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.

References

No references.

Sublime Security

Created May 29th, 2026 • Last updated May 29th, 2026

Feed Source

Sublime Core Feed

Source

GitHub

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'
        )
)

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