Spoofing Super Admins: An IDOR Vulnerability in Enterprise Message Forwarding By Savan Chotaliya

During a recent bug bounty engagement on a corporate workspace platform, I discovered an Insecure Direct Object Reference (IDOR) vulnerability within the message forwarding endpoint. By manipulating a client-side parameter, I successfully bypassed authorization controls to spoof messages, making them appear as if they were forwarded by a Super Admin or any other organizational user.

The Discovery: Leaking the Target User ID

To spoof a user, I first needed their internal account ID. The application inadvertently exposed this during normal messaging operations. When initiating a standard chat with any user in the organization, the HTTP request and response traffic plainly revealed the recipient's internal user_id.

This design flaw provided a reliable method to harvest the IDs of high-privilege accounts, such as Super Admins, simply by sending them a direct message or pulling their profile from the corporate directory.

The Exploit: Parameter Tampering

Armed with a target Super Admin ID, I moved to the message forwarding feature. I routed my web traffic through Burp Suite to intercept the API calls and executed the following sequence:

1. Initiate Forwarding: I selected a benign message in my own chat and clicked the "Forward" button, choosing a test recipient.
2. Intercept the Request: In Burp Suite, I caught the outbound HTTP POST request directed at the forwarding endpoint.
3. Modify the Parameter: The JSON payload included a highly vulnerable parameter: "forwardedFrom": "my_own_user_id".
4. Execute the Spoof: I swapped my user ID with the harvested Super Admin ID and forwarded the modified request to the server.

The application processed the tampered request without validating if the current active session matched the forwardedFrom value. The recipient received the message, and the UI displayed the Super Admin's name as the original sender of the forwarded text.

Business Impact

This logic flaw presents a severe internal social engineering and phishing risk. An attacker with a low-level compromised account could weaponize this to:

• Spoof IT administrators requesting sensitive credentials or immediate password resets.
• Impersonate executives directing finance teams to approve fraudulent wire transfers.
• Distribute malicious links under the guise of an urgent, mandatory company-wide IT update.

Remediation & Recommendations

To secure the forwarding endpoint, the development team must shift trust away from client-supplied data and enforce strict server-side validation.

• Enforce Session-Based Authorization: The server must ignore the forwardedFrom parameter in the client request. Instead, it should automatically extract the sender's identity directly from the authenticated session token (e.g., JWT or session cookie) of the user making the request.
• Implement Server-Side Lineage Tracking: If the application needs to display the original author of a forwarded message, it should query the database for the original message ID rather than trusting the client to declare who the author is.
• Audit API Endpoints for Object References: Ensure that every API endpoint explicitly verifies that the user invoking the action has the correct permissions to perform that specific action on the requested data object.