Google Workspace Object Copied to External Drive with App Consent

Last updated 5 days ago on 2024-09-23

Created 2 years ago on 2023-03-07

About

Detects when a user copies a Google spreadsheet, form, document or script from an external drive. Sequence logic has been added to also detect when a user grants a custom Google application permission via OAuth shortly after. An adversary may send a phishing email to the victim with a Drive object link where "copy" is included in the URI, thus copying the object to the victim's drive. If a container-bound script exists within the object, execution will require permission access via OAuth in which the user has to accept.

Tags

Domain: CloudData Source: Google WorkspaceTactic: Initial Access

Severity

medium

Risk Score

MITRE ATT&CK™

Initial Access (TA0001)(opens in a new tab or window)

↳ Phishing (T1566)(opens in a new tab or window)

False Positive Examples

Google Workspace users typically share Drive resources with a shareable link where parameters are edited to indicate when it is viewable or editable by the intended recipient. It is uncommon for a user in an organization to manually copy a Drive object from an external drive to their corporate drive. This may happen where users find a useful spreadsheet in a public drive, for example, and replicate it to their Drive. It is uncommon for the copied object to execute a container-bound script either unless the user was intentionally aware, suggesting the object uses container-bound scripts to accomplish a legitimate task.

License

Elastic License v2(opens in a new tab or window)

Definition

Rule Type: Event Correlation Rule
Integration Pack: Prebuilt Security Detection Rules
Index Patterns: filebeat-*logs-google_workspace*
Related Integrations: google_workspace(opens in a new tab or window)
Query

sequence by source.user.email with maxspan=3m
[file where event.dataset == "google_workspace.drive" and event.action == "copy" and

    /* Should only match if the object lives in a Drive that is external to the user's GWS organization */
    google_workspace.drive.owner_is_team_drive == "false" and google_workspace.drive.copy_type == "external" and

    /* Google Script, Forms, Sheets and Document can have container-bound scripts */
    google_workspace.drive.file.type: ("script", "form", "spreadsheet", "document")]

[any where event.dataset == "google_workspace.token" and event.action == "authorize" and

    /* Ensures application ID references custom app in Google Workspace and not GCP */
    google_workspace.token.client.id : "*apps.googleusercontent.com"]

Install detection rules in Elastic Security

Detect Google Workspace Object Copied to External Drive with App Consent in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).