Ssrf Server Side in Mongodb
How Ssrf Server Side Manifests in Mongodb
Server-Side Request Forgery (SSRF) in MongoDB contexts often occurs when application code uses untrusted user input to construct MongoDB connection strings or when MongoDB drivers are used to make outbound network requests. The most common MongoDB-specific SSRF pattern involves the mongodb:// URI scheme being manipulated to connect to internal services rather than the intended database.
A classic example is when an application accepts a MongoDB connection string from a user or configuration parameter without validation. An attacker could modify the URI to point to internal services like:
// Vulnerable: User-controlled MongoDB URI
const uri = req.query.mongoUri || process.env.MONGO_URI;
const client = new MongoClient(uri);
client.connect();
An attacker could supply mongodb://localhost:27017/admin?appName=http://internal-service:8080 or craft more sophisticated payloads that cause the MongoDB driver to make requests to internal network services. The MongoDB driver might attempt to connect to these URIs, potentially exposing internal services that weren't meant to be accessible externally.
Another Mongodb-specific SSRF vector occurs in replica set configurations where applications dynamically construct connection strings from user input. Consider this vulnerable pattern:
// Vulnerable: Dynamic replica set construction
const hosts = req.body.hosts; // e.g., ["host1:27017", "host2:27017"]
const replicaSet = req.body.replicaSet || 'rs0';
const uri = `mongodb://${hosts.join(',')}/?replicaSet=${replicaSet}`;
An attacker could inject hosts pointing to internal services, causing the MongoDB driver to attempt connections that result in SSRF. This is particularly dangerous in cloud environments where metadata services (like AWS EC2 metadata at 169.254.169.254) might be accessible from the application's network context.
MongoDB's GridFS feature can also be abused for SSRF when file URLs are constructed from user input. If an application allows users to specify GridFS bucket names or file paths that are then used to construct MongoDB queries, an attacker might manipulate these to access internal resources or trigger unintended network requests.
Mongodb-Specific Detection
Detecting SSRF vulnerabilities in MongoDB contexts requires both static code analysis and runtime scanning. For static analysis, look for patterns where MongoDB connection strings are constructed from untrusted sources. middleBrick's scanning engine specifically identifies these patterns by analyzing your application's code and configuration files for MongoDB URI construction vulnerabilities.
middleBrick's MongoDB SSRF detection includes several key checks:
- URI Validation: Scans for MongoDB connection strings that accept user input without proper validation or whitelisting of allowed hosts
- Replica Set Analysis: Identifies dynamic construction of replica set configurations where host lists come from untrusted sources
- GridFS Path Traversal: Detects when GridFS bucket names or file paths are constructed from user input without validation
- Driver Version Checks: Verifies you're using MongoDB drivers with built-in SSRF protections and security patches
During runtime scanning, middleBrick tests your MongoDB endpoints by attempting controlled SSRF payloads and monitoring for outbound connections to restricted networks. The scanner uses a variety of techniques including:
// Example of SSRF test payload for MongoDB
const testPayloads = [
'mongodb://localhost:27017/admin?appName=http://169.254.169.254/latest/meta-data/',
'mongodb://[::1]:27017/admin',
'mongodb://internal-service:8080/admin',
'mongodb://example.com:80/admin?appName=mongodb-ssrf-test'
];
middleBrick also analyzes your MongoDB configuration files (like mongod.conf) for network binding settings that might expose internal services to SSRF attacks. The scanner checks if MongoDB is bound to 0.0.0.0 or :: (all interfaces) rather than specific internal IPs, which could allow SSRF to reach the database from unexpected network paths.
For applications using MongoDB Atlas or other cloud MongoDB services, middleBrick specifically tests for SSRF vulnerabilities that could expose cloud metadata services or internal VPC services that might be accessible from your application's network context.
Mongodb-Specific Remediation
Remediating MongoDB SSRF vulnerabilities requires a defense-in-depth approach. The first and most critical step is input validation and sanitization of all MongoDB connection strings and configuration parameters. Use a strict whitelist approach rather than blacklisting:
// Secure: Whitelist approach for MongoDB URIs
const allowedHosts = ['db-primary.example.com', 'db-secondary.example.com'];
const allowedPorts = [27017, 27018, 27019];
function validateMongoUri(uri) {
const url = new URL(uri);
if (url.protocol !== 'mongodb:') {
throw new Error('Invalid protocol');
}
const host = url.hostname;
const port = url.port ? parseInt(url.port) : 27017;
if (!allowedHosts.includes(host) || !allowedPorts.includes(port)) {
throw new Error('Host not in allowed list');
}
return true;
}
// Usage
const uri = req.query.mongoUri;
try {
validateMongoUri(uri);
const client = new MongoClient(uri);
await client.connect();
} catch (error) {
console.error('MongoDB URI validation failed:', error.message);
throw error;
}
For replica set configurations, validate each host in the replica set configuration:
// Secure: Validate replica set hosts
function validateReplicaSetHosts(hosts) {
const allowedHosts = ['db-primary.example.com:27017', 'db-secondary.example.com:27017'];
for (const host of hosts) {
if (!allowedHosts.includes(host)) {
throw new Error(`Host ${host} not in allowed list`);
}
}
return true;
}
// Usage
const hosts = req.body.hosts;
try {
validateReplicaSetHosts(hosts);
const uri = `mongodb://${hosts.join(',')}/?replicaSet=rs0`;
const client = new MongoClient(uri);
await client.connect();
} catch (error) {
console.error('Replica set validation failed:', error.message);
throw error;
}
Another critical remediation is network segmentation. Configure your MongoDB instances to bind only to specific internal IPs rather than all interfaces:
For applications using MongoDB drivers, ensure you're using the latest versions with built-in SSRF protections. Modern MongoDB drivers include security features that reject suspicious connection strings and provide better error handling for malformed URIs.
Implement proper logging and monitoring for MongoDB connection attempts. Monitor for unusual connection patterns, such as connections from unexpected IP addresses or attempts to connect to internal services. Use MongoDB's built-in auditing features to track connection attempts and query patterns.
Finally, consider using MongoDB's authentication and authorization features to limit what connections can do even if SSRF occurs. Configure role-based access control so that even if an attacker can connect to your MongoDB instance, they have limited permissions to execute queries or access data.
Frequently Asked Questions
How does SSRF in MongoDB differ from regular SSRF vulnerabilities?
mongodb:// URI scheme, replica set configurations, and GridFS operations. The MongoDB driver might attempt to connect to internal services when parsing these URIs, making it a distinct attack vector that requires MongoDB-specific detection and remediation approaches.