Prevent NoSQL Injection Attacks · Mesrai Marketplace

Why this matters

Unsanitized user input in NoSQL queries can allow attackers to manipulate database queries, leading to data leaks or unauthorized modifications.

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Request.Query["filterDefinition"];

        await collection.FindAsync(filter)
    }
}

Prefer

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Builders<BsonDocument>.Filter.Eq("Usertitle", "Example");

        await collection.FindAsync(filter)
    }
}

More snippets

Bad

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Request.Query["filterDefinition"];

        await collection.FindAsync(filter)
    }
}

Good

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Builders<BsonDocument>.Filter.Eq("Usertitle", "Example");

        await collection.FindAsync(filter)
    }
}

Related rules

From the same buckets as this rule.

Critical

Always sanitize user inputs

Check if user inputs are sanitized before being used in rendering or database queries. Unsanitized inputs can lead to injection vulnerabilities like XSS or SQL injection.

security-hardening

Critical

Always Verify Server Certificates in SSL/TLS Connections

Ensure that SSL/TLS certificate validation is always enabled to prevent Man-in-the-Middle (MitM) attacks.

security-hardening

Critical

Avoid modifying built-in prototypes

Detect modifications to built-in prototypes. Modifying built-in objects can lead to compatibility issues and unexpected behavior. Recommend creating helper functions instead.

maintainabilitysecurity-hardening

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Request.Query["filterDefinition"];

        await collection.FindAsync(filter)
    }
}

Prefer

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Builders<BsonDocument>.Filter.Eq("Usertitle", "Example");

        await collection.FindAsync(filter)
    }
}

More snippets

Bad

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Request.Query["filterDefinition"];

        await collection.FindAsync(filter)
    }
}

Good

using MongoDB.Driver;
using MongoDB.Bson;

[ApiController]
[Route("Example")]
public class ExampleController: ControllerBase
{
    private string connectionString;

    [Route("Example")]
    public async Task<string> Example()
    {
        var client     = new MongoClient(connectionString);
        var database   = client.GetDatabase("example");
        var collection = database.GetCollection<Message>("messages");

        var filterDefinition = Builders<BsonDocument>.Filter.Eq("Usertitle", "Example");

        await collection.FindAsync(filter)
    }
}

Related rules

From the same buckets as this rule.

Critical

Always sanitize user inputs

Check if user inputs are sanitized before being used in rendering or database queries. Unsanitized inputs can lead to injection vulnerabilities like XSS or SQL injection.

security-hardening

Critical

Always Verify Server Certificates in SSL/TLS Connections

Ensure that SSL/TLS certificate validation is always enabled to prevent Man-in-the-Middle (MitM) attacks.

security-hardening

Critical

Avoid modifying built-in prototypes

Detect modifications to built-in prototypes. Modifying built-in objects can lead to compatibility issues and unexpected behavior. Recommend creating helper functions instead.

maintainabilitysecurity-hardening