NoSQL Injection

NoSQL injection happens when unvalidated inputs are used to manipulate NoSQL queries, leading to unintended commands being executed. This can result in unauthorized access or exposure of sensitive data. Applications that don’t sanitize inputs properly are at risk. To prevent it, ensure input validation and use query parameterization.

This blog explores the intricacies of NoSQL injection, highlighting its mechanisms, common attack vectors, and effective prevention strategies. It delves into how vulnerabilities arise from improper input validation and weak query construction.

What is NoSQL?

NoSQL, or "not only SQL," refers to a category of database management systems that handle diverse data models beyond the traditional relational structure. Unlike relational databases with fixed schemas, NoSQL databases store unstructured or semi-structured data and offer flexibility for distributed systems. They support large-scale, modern applications by providing scalability and performance optimization.

What is NoSQL Injection?

NoSQL injection allows attackers to inject malicious code into queries executed by NoSQL databases, leading to unauthorized access, data manipulation, and potentially full control over the application.

NoSQL injection attackers target non-relational databases like MongoDB and Cassandra. They exploit the flexible data structures and query languages of these databases. Attackers manipulate input that applications pass directly to the database without proper validation. This allows them to bypass authentication or access sensitive data.

Attackers employ two main types of NoSQL injection attacks. Syntax injection alters query syntax to inject malicious code. Operator injection exploits NoSQL query operators like $where in MongoDB to execute arbitrary commands.

How Does NoSQL Injection Occur?

NoSQL injection occurs when attackers inject malicious code into database queries, exploiting weak input validation or improper query construction. By directly incorporating unsanitized user inputs, applications become vulnerable to these attacks, leading to serious security breaches.

Exploiting Weak Query Construction

NoSQL injection often exploits weak query construction. When applications use user inputs directly in database queries without proper validation, attackers can inject harmful code.

Example of Weak Query Construction In a MongoDB-based authentication system, an application may execute a query like this:

Users.findOne({
    "name": req.body.name,
    "password": req.body.password
});

If attackers submit malicious inputs(JSON), such as:

This causes the query to return true for all entries, bypassing authentication and granting unauthorized access.

Lack of Input Validation

Insufficient input validation is another common vulnerability that leads to NoSQL injection. When applications fail to sanitize inputs, attackers can inject additional query operators or malformed data.

Example of Lack of Input Validation Consider a MongoDB query without input validation:

db.users.find({
    "username": req.body.username,
    "password": req.body.password
});

An attacker could submit(JSON):

This always evaluates to true, returning all user records, thereby exposing sensitive data.

Common Attack Vectors

Attackers exploit various techniques to manipulate database queries, enabling unauthorized access or control over sensitive data.

1. Tautology Injection: Attackers inject conditions that always evaluate to true, allowing them to bypass authentication.

   • Example(JSON)

     

2. JavaScript Injection: NoSQL databases like MongoDB allow JavaScript execution within queries, which attackers can exploit to inject malicious JavaScript.

   • Example

   db.collection.find({
       $where: "this.username === 'admin' && this.password === 'password'"
   });

   Attackers can manipulate this query to execute arbitrary JavaScript code.

3. Timing Attacks: Attackers use timing-based payloads to infer information from the database based on response times.

   • Example(JSON)

     

   A delayed response confirms the injection's success, revealing vulnerabilities.

Examples of NoSQL Injection in MongoDB

NoSQL injection presents a significant vulnerability that enables attackers to manipulate queries sent to NoSQL databases like MongoDB. This manipulation can result in unauthorized data access or even complete control over the database. Below are examples illustrating how attackers can exploit NoSQL injection, specifically in MongoDB.

1. Syntax Injection

Attackers can break the query syntax to inject their own payloads. Consider a vulnerable application that constructs a MongoDB query using user input without proper sanitization:

db.users.find({ username: userInput });

If an attacker manipulates userInput as follows:

admin' || '1'=='1

The resulting query becomes:

db.users.find({ username: 'admin' || '1'=='1' });

This modification effectively returns all users because the condition is always true.

2. Operator Injection

In MongoDB, attackers can inject various operators to alter query behavior. For example, if an application accepts a username and password via a POST request:

An attacker might modify the input(JSON) to include MongoDB operators:

This query matches any user whose username is not "foo" and password is not "bar," potentially granting unauthorized access if an admin user exists.

3. Exploiting the $where Operator

The $where operator in MongoDB allows JavaScript expressions in queries, which attackers can exploit for injection attacks. For instance:

db.users.find({ $where: "this.username == '" + userInput + "'" });

If an attacker sets userInput to:

admin' && this.password == 'a' || 'a'=='b

The query becomes:

db.users.find({ $where: "this.username == 'admin' && this.password == 'a' || 'a'=='b'" });

This injection enables the attacker to extract sensitive information character by character from the password field.

4. Authentication Bypass

Consider a login function that directly uses user inputs in a query:

An attacker could send the following payloads(JSON) in a POST request:

This payload bypasses authentication checks by matching any username and password that are not null.

NoSQL Injection vs SQL Injection

This comparison highlights the critical distinctions and similarities between NoSQL and SQL injection attacks, emphasizing the need for tailored security strategies for each type of database.

NoSQL Injection CVEs

Several documented security incidents have resulted from NoSQL injection vulnerabilities, as evidenced by the following Common Vulnerabilities and Exposures (CVEs):

CVE-2022-35246

A NoSQL injection vulnerability in the getS3FileUrl Meteor server method affects Rocket.Chat versions prior to v5, v4.8.2, and v4.7.5. This flaw enables unauthorized users to access file upload URLs they shouldn't be able to view. Attackers can exploit this vulnerability to gain access to restricted files and potentially compromise sensitive information.

CVE-2021-22911

Inadequate input sanitization in Rocket.Chat server versions 3.11, 3.12, and 3.13 results in a NoSQL injection vulnerability. Unauthenticated users can exploit this flaw to inject malicious input, potentially leading to remote code execution. The lack of proper validation exposes the system to various attacks, including privilege escalation.

CVE-2024-28192

YourSpotify version <1.8.0 contains a NoSQL injection vulnerability in the public access token processing. Attackers can exploit this flaw to bypass public token authentication, gaining unauthorized access without user interaction or prior knowledge. Version 1.8.0 fixes this vulnerability, and developers recommend updating to the latest version to mitigate the risk.

CVE-2019-10758

A NoSQL injection vulnerability affects Mongoose versions before 5.7.5. Attackers can craft malicious payloads to exploit the query population system in mongoose, bypassing authentication and authorization mechanisms. This vulnerability allows unauthorized access to protected resources, making it crucial to upgrade to the patched version.

CVE-2020-7699

KeystoneJS version 4.0.0-rc.5 contains a NoSQL injection vulnerability in the query parameter. Malicious users can exploit this flaw to inject arbitrary NoSQL queries into KeystoneJS's MongoDB query system, leading to unauthorized access to database records. Later versions address this vulnerability, and updating is essential to prevent exploitation.

Ways To Prevent NoSQL Injection Attacks

Developers must implement several effective strategies to prevent NoSQL injection attacks and safeguard their applications against unauthorized data access and manipulation.

Input Validation

Start preventing NoSQL injection with robust input validation. Strictly validate user inputs to ensure only expected data types and formats pass through. For example, before executing a MongoDB query to authenticate a user, check that the username and password contain only alphanumeric characters. Reject inputs with special characters or MongoDB operators like $ne or $gt to prevent malicious query alterations.

Parameterized Queries

Use parameterized queries to prevent the execution of untrusted input as part of the query logic. Treat inputs as data values instead of directly concatenating them into queries. For instance, when searching for a user, use MongoDB's $eq operator to ensure that the application treats the username and password strictly as values, not executable commands, mitigating the risk of injection.

Least Privilege

Apply the principle of least privilege to database permissions to limit the impact of potential attacks. Grant only the necessary access rights for each user or service to minimize damage in the event of an injection attack. For example, restrict write and delete permissions to administrative accounts while allowing read-only access for regular users to protect sensitive data from unauthorized changes.

Security Audits

Conduct regular security audits to identify vulnerabilities before attackers can exploit them. Perform frequent audits and code reviews to assess the safety of query construction and input handling. For example, have code reviewers check that all user inputs undergo validation and sanitization before incorporation into NoSQL queries. Ensure that these audits also verify that database user permissions follow best practices, adhering to the principle of least privilege.

Query Escaping

Escape special characters in queries to add an extra layer of protection against NoSQL injection. Ensure the application treats characters that could be interpreted as operators or executable code as plain text. For example, when processing user inputs in a MongoDB query, escape characters like $ or {} to prevent their misuse in manipulating query logic.

Disabling Unnecessary Features

Disable unused or unnecessary features of the database to reduce the attack surface for NoSQL injection. For example, turn off server-side JavaScript execution in MongoDB to prevent attackers from injecting malicious scripts into queries. Limit the functionality available within the database to reduce the opportunities for exploitation.

Final Thoughts

NoSQL injection poses significant risks to applications that fail to validate user inputs adequately. By understanding the types of attacks, common vulnerabilities, and effective prevention strategies, organizations can safeguard their NoSQL databases against unauthorized access and data manipulation.

Implementing robust security measures is essential, and tools like Akto can help automate the detection of security vulnerabilities in NoSQL applications. Akto provides real-time monitoring and proactive security measures to ensure the databases remain resilient against threats. Don't leave the data security to chance; try the Akto demo today to fortify the applications against cyber attacks.