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NoSQL Injection - Exploiting Unvalidated User Input in NoSQL Databases

Injection AttacksDatabase SecurityAuthentication BypassWeb Application VulnerabilitiesSecure Coding Practices

NoSQL Injection occurs when untrusted user input is improperly concatenated into a NoSQL query, allowing attackers to manipulate database queries. Unlike traditional SQL injection, NoSQL injection often exploits operators and syntax to bypass authentication or extract sensitive data.

Key Points

  • Injection Mechanism: Attackers inject NoSQL-specific syntax or operators ($ne, $gt, $or, etc.) into queries to manipulate their behavior.
  • Authentication Bypass: By crafting input such as {"username": {"$ne": ""}, "password": {"$ne": ""}}, an attacker can force the database to return any user document.
  • Data Extraction: Using blind injection techniques, an attacker can infer data from error messages or query responses.

Detailed Explanation

Injection Mechanism

Attackers inject NoSQL-specific syntax or operators into queries to manipulate their behavior. Common operators include $ne, $gt, $or, etc.

Authentication Bypass

By crafting input such as {"username": {"$ne": ""}, "password": {"$ne": ""}}, an attacker can force the database to return any user document, effectively bypassing authentication mechanisms.

Data Extraction

Using blind injection techniques, an attacker can infer data from error messages or query responses. This method allows attackers to extract sensitive information without direct access to the database.

Practical Example

$user = $_POST['user'];
$pass = $_POST['pass'];
$q = new MongoDB\Driver\Query(['username' => $user, 'password' => $pass]);
$record = $con->executeQuery('myapp.login', $q);

Exploit Input:

{"username": {"$ne": "xxxx"}, "password": {"$ne": "yyyy"}}

This tricks the query into returning all user records, allowing unauthorized access.

Real-World Application

NoSQL injections have been used to bypass login authentication in MongoDB-based applications, leading to unauthorized access and data breaches.

Key Takeaways

  • Always use parameterized queries and input validation to prevent NoSQL injection.
  • Do not directly concatenate user input into database queries.
  • Be aware of NoSQL-specific operators ($ne, $gt, $regex) that can be exploited in injections.

Learn More

For further reading on NoSQL injection and how to protect against it, consider exploring resources on secure coding practices and database security.