Attack Chain

1. An attacker identifies an application using a vulnerable version of Mongoose with sanitizeFilter enabled.
2. The attacker crafts a malicious payload containing a $nor operator with an embedded, unsanitized operator (e.g., $ne, $gt, or $regex).
3. The attacker injects the malicious payload into a user-controlled input field, such as a search parameter or login field.
4. The application passes the unsanitized input directly to a Mongoose query method (e.g., Model.findOne(req.body)).
5. Mongoose’s sanitizeFilter function fails to properly sanitize the $nor operator, allowing the malicious operator to bypass sanitization.
6. The malicious operator is executed against the MongoDB database.
7. The attacker bypasses authentication, gains unauthorized data access, or exfiltrates sensitive information.

Impact

Successful exploitation of this vulnerability can lead to significant impact, including authentication bypass, where attackers can gain access to user accounts without proper credentials. Unauthorized data access allows attackers to view and modify sensitive data that they should not have access to. Data exfiltration enables attackers to steal confidential information from the database. Organizations using vulnerable versions of Mongoose are at risk.

Recommendation

• Upgrade to Mongoose version 6.13.9 or later, 7.8.9 or later, 8.22.1 or later, or 9.1.6 or later to patch the vulnerability as described in GHSA-wpg9-53fq-2r8h.
• Deploy the following Sigma rule to detect the use of $nor in query parameters to webserver logs and tune for your environment.
• Implement a workaround by deleting $nor keys or using an additional schema validation library as recommended in GHSA-wpg9-53fq-2r8h.