A recently identified security vulnerability in the GitHub repository nocodb/nocodb has been assigned the identifier CVE-2023-5104. This vulnerability, classified as improper input validation, could have potential exploitation risks if left unpatched. In this post, we will deep dive into the problematic code snippet, the origin of the vulnerability, and how it can be exploited. Finally, we will also discuss the remediation measures available to address this security issue.

Vulnerability Details

CVE-2023-5104 is an improper input validation vulnerability that affects the nocodb/nocodb GitHub repository before version .96.. Input validation is a critical function in web applications and APIs, as it helps prevent attackers from sending malicious data that could lead to unintended consequences, such as code execution, data leaks, or denial of service. In the case of this vulnerability, the input validation process failed to properly sanitize user input or validate it against a whitelist of allowed characters.

Refer to the following resources for the original references regarding this vulnerability

- NVD - CVE-2023-5104
- GitHub Advisory for nocodb/nocodb

Let's review the affected code snippet to better understand the issue. Here's the code in question, responsible for handling user input:

# nocodb/nocodb/some_module.py

def handle_user_input(data):
   # ... some code ...
   unsanitized_input = data.get('user_input', '').strip()
   # ... process the input ...

In the code above, the data parameter is expected to be a dictionary containing a key named 'user_input'. The handle_user_input function retrieves the value for that key and stores it in the unsanitized_input variable. The problem lies in the fact that the input is not properly validated or sanitized before it gets processed further.

Exploitation

An attacker could potentially exploit this vulnerability by sending crafted user input containing malicious characters or code, relying on the fact that the input validation process is insufficient. As a hypothetical example, consider the following malicious input payload:

{
  "user_input": "'); DROP TABLE users; --'"
}

In this example, an attacker attempts to send an SQL injection payload through the 'user_input' key. The vulnerable code processes this data without proper input validation or sanitization, which could lead to the execution of the SQL injection payload in the context of the database server, causing data loss or unauthorized access to sensitive information.

Remediation

To address this vulnerability, it is crucial to update the nocodb/nocodb repository to version .96. or later. The issue is fixed in the newer releases, where proper input validation and sanitization are implemented. For reference, here is the updated code snippet with proper input validation added:

# nocodb/nocodb/some_module_updated.py
import re

def handle_user_input(data):
   # ... some code ...
   unsanitized_input = data.get('user_input', '').strip()
   sanitized_input = re.sub(r"[^A-Za-z-9_]+", "", unsanitized_input) # Only allow alphanumeric characters and underscores
   # ... process the sanitized input ...

The updated code above now includes the use of the re.sub() function to remove all characters not present in the whitelist of allowed characters. This approach dramatically reduces the risk of the vulnerability being exploited.

Conclusion

CVE-2023-5104 is a security vulnerability caused by improper input validation in the nocodb/nocodb GitHub repository prior to version .96.. Ensuring secure handling of user input is a critical aspect of preventing various attacks, including code injection, data leakage, and denial of service. Updating to the latest, patched version of the repository and following best practices for input validation can effectively mitigate the risk associated with this vulnerability.

Timeline

Published on: 09/21/2023 09:15:00 UTC
Last modified on: 09/22/2023 13:48:00 UTC