Horizon Alert
Summary of the vulnerability and why it matters
A vulnerability in Etherpad, a collaborative editing tool, could allow unauthorized users to access and modify documents. This issue stems from how the system verifies administrative privileges for certain API requests, potentially exposing sensitive information or leading to data loss.
- Non-admins can perform administrative actions.
- Confirms risk to collaborative document integrity.
- Verify relevance and exposure to your Etherpad instances.
Attack Path
How an attacker could exploit the issue
An attacker with a valid signed token can bypass authorization checks in Etherpad's API, specifically when interacting with administrative functions. By exploiting a flaw in how the `admin` claim is handled in the OAuth2 flow, a non-admin user can gain the ability to perform actions such as modifying, deleting, copying, or listing pads and authors, potentially leading to unauthorized data access or manipulation.
- Requires a valid signed token.
- Invokes administrative API endpoints.
- Allows data disclosure, modification, or deletion.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, a non-administrative user with a valid signed token could invoke administrative functions. This could allow for the disclosure, modification, or deletion of pads across the entire Etherpad instance.
- Sensitive pad data could be exposed.
- Unauthorized users may modify or delete pads.
- Data disclosure and modification are possible.
Operational Fix
Recommended remediation, mitigation, and detection steps
Responsible teams will likely include application owners, platform teams, and security operations, given Etherpad's role as a collaborative web editor often exposed externally. The immediate first step is to identify all Etherpad instances, determine their reachability and business criticality, and locate the accountable owner to plan remediation based on risk.
- Application owners should own the issue.
- Verify instance reachability and criticality first.
- Plan remediation based on assessed risk.
