Source: contact@wpscan.com
The Ninja Forms WordPress plugin before 3.13.3 allows unauthenticated attackers to generate valid access tokens via the REST API which can then be used to read form submissions.
Unauthenticated attackers can exploit a vulnerability in the Ninja Forms WordPress plugin to generate valid access tokens, granting them the ability to read sensitive form submissions. This allows for the theft of confidential data and potential further compromise of the targeted WordPress installation.
Step 1: REST API Endpoint Discovery: The attacker identifies the vulnerable REST API endpoint within the Ninja Forms plugin. This endpoint is responsible for generating access tokens. Step 2: Unauthenticated Request: The attacker crafts an unauthenticated request to the identified REST API endpoint. The request may include specific parameters or data that the plugin incorrectly trusts. Step 3: Token Generation: Due to the vulnerability, the plugin processes the unauthenticated request and generates a valid access token. This token is likely returned in the response. Step 4: Token Usage: The attacker uses the generated access token to authenticate subsequent requests to the Ninja Forms REST API. These requests are now authorized as if they were made by a legitimate user. Step 5: Data Exfiltration: The attacker uses the token to access and retrieve sensitive form submission data, including personal information, contact details, and other confidential information.
The vulnerability stems from a flaw in the REST API authentication mechanism of the Ninja Forms plugin. Specifically, the plugin fails to properly validate requests, allowing unauthenticated users to generate valid access tokens. This likely involves a missing or flawed authorization check within the token generation process. The root cause is a logic error in how the plugin handles user authentication and authorization when creating access tokens via the REST API. The plugin likely trusts the request parameters without proper validation, leading to the creation of tokens for unauthorized users. This could be due to a missing is_user_logged_in() check or similar authentication validation. The lack of proper input validation on the request parameters used to generate the token is also a contributing factor.
This vulnerability is attractive to a wide range of attackers, including script kiddies and financially motivated cybercriminals. It is also likely to be exploited by nation-state actors seeking to gather intelligence. CISA KEV status is likely given the severity and ease of exploitation.
Monitor WordPress access logs for unusual REST API requests to Ninja Forms endpoints, especially those originating from unexpected IP addresses or user agents.
Analyze HTTP traffic for suspicious patterns, such as repeated requests to the token generation endpoint without proper authentication headers.
Implement Web Application Firewall (WAF) rules to block or flag requests to the vulnerable endpoint that lack proper authentication.
Monitor file system changes within the WordPress installation for unauthorized modifications to plugin files or database entries.
Examine server logs for error messages related to Ninja Forms REST API calls, which may indicate exploitation attempts.
Update the Ninja Forms plugin to version 3.13.3 or later.
Implement a Web Application Firewall (WAF) to filter malicious requests.
Review and harden the WordPress configuration, including user access controls and file permissions.
Regularly back up the WordPress database and file system.
Implement a security audit of the WordPress installation and plugins.
Enforce strong password policies for all user accounts.
Disable the REST API if not required or restrict access to authenticated users only.