Symlink Attack in Cockroachdb

Symlink attacks in Cockroachdb exploit the database's interaction with the underlying filesystem, particularly during backup, restore, and data import operations. Cockroachdb's distributed architecture stores data across multiple nodes, but when performing certain file operations, it can inadvertently follow symbolic links, allowing attackers to manipulate file paths and access unauthorized data.

The most common attack vector occurs during Cockroachdb's IMPORT and BACKUP operations. When Cockroachdb processes file paths for these operations, it may not properly validate whether a path is a symbolic link. An attacker with filesystem access can create symlinks that point to sensitive system files or other databases, causing Cockroachdb to read or write to unintended locations.

Consider this vulnerable pattern in Cockroachdb's backup scripts:

BACKUP DATABASE mydb TO 'gs://my-bucket/backups/mydb_backup.sql';

If an attacker manipulates the gs://my-bucket/backups/ path to include symlinks, Cockroachdb might write backup data to unexpected locations. This becomes particularly dangerous when combined with Cockroachdb's default permissions, where the database process often runs with elevated privileges.

Another manifestation occurs in Cockroachdb's IMPORT functionality. When importing data from external sources, Cockroachdb resolves file paths to read source data. If an attacker creates a symlink that points to /etc/passwd or other sensitive files, and the import path resolves through this symlink, Cockroachdb could inadvertently import sensitive system data.

The distributed nature of Cockroachdb adds complexity. When a node processes a symlink, it might resolve it differently than other nodes, leading to inconsistent behavior across the cluster. This inconsistency can cause data corruption or expose different data to different nodes, creating a security nightmare.

Real-world examples show attackers leveraging this in containerized deployments. When Cockroachdb runs in Docker with mounted volumes, symlinks in the host filesystem can traverse into container boundaries, allowing attackers to access files outside the intended database directories.

Detecting symlink attacks in Cockroachdb requires both runtime monitoring and static analysis of database operations. middleBrick's API security scanner includes specific checks for Cockroachdb symlink vulnerabilities by examining how the database handles file paths and symbolic links.

middleBrick scans Cockroachdb endpoints by sending requests that attempt to trigger symlink resolution. The scanner tests backup and import endpoints with specially crafted paths containing symlinks, then analyzes the responses for signs of path traversal or unauthorized file access. This black-box approach requires no credentials or database access, making it ideal for testing production systems.

Key detection patterns include:

• Path Resolution Analysis: middleBrick examines how Cockroachdb resolves file paths in backup/restore operations, looking for patterns that might follow symlinks
• Permission Escalation Checks: The scanner tests whether Cockroachdb operations can access files outside designated directories
• Import Validation: middleBrick specifically tests import endpoints with symlinked paths to verify proper validation

Beyond automated scanning, Cockroachdb administrators should monitor for suspicious file operations. Enable Cockroachdb's audit logging and watch for backup operations writing to unexpected locations or import operations accessing unusual files.

middleBrick's LLM security features also detect if your Cockroachdb setup involves AI/ML components that might be vulnerable to symlink attacks. For example, if you're using vector embeddings stored in Cockroachdb and serving them through an AI API, middleBrick tests for prompt injection that could manipulate file paths.

The scanner provides a security score (0-100) with specific findings about symlink vulnerabilities, including severity levels and remediation guidance. Critical findings indicate that Cockroachdb is following symlinks to sensitive locations, while high findings suggest potential path traversal in backup operations.

Remediating symlink attacks in Cockroachdb requires a multi-layered approach combining configuration changes, code hardening, and operational practices. The goal is to ensure Cockroachdb never follows symlinks to unauthorized locations.

First, implement strict path validation in your Cockroachdb operations. When performing backups or imports, always use absolute paths and validate they don't contain symlinks:

func validatePath(path string) error {
    // Check if path is a symlink
    fileInfo, err := os.Lstat(path)
    if err != nil {
        return err
    }
    if fileInfo.Mode()&os.ModeSymlink != 0 {
        return errors.New("symlink detected in path")
    }
    return nil
}

// Use in backup scripts
func safeBackup(db *sql.DB, path string) error {
    if err := validatePath(path); err != nil {
        return err
    }
    
    // Only allow paths within designated backup directory
    if !strings.HasPrefix(filepath.Clean(path), "/var/lib/cockroach/backups/") {
        return errors.New("backup path outside allowed directory")
    }
    
    _, err := db.Exec(fmt.Sprintf("BACKUP DATABASE mydb TO '%s'", path))
    return err
}

For import operations, Cockroachdb provides the IMPORT statement with path validation options. Always specify the exact file format and validate source paths:

-- Secure import with explicit format and path validation
IMPORT TABLE users (id UUID PRIMARY KEY, name STRING)
CSV DATA ('gs://my-bucket/data/users.csv')
WITH delimiter = ',', header = true;

-- Verify the source file exists and is not a symlink
SELECT pg_ls_dir('gs://my-bucket/data/');

Configure Cockroachdb to run with minimal filesystem permissions. Create a dedicated user for the Cockroachdb process that cannot access sensitive system directories:

# Create restricted user
useradd -r -s /bin/false -d /var/lib/cockroach cockroachdb

# Set strict permissions on data directories
chown -R cockroachdb:cockroachdb /var/lib/cockroach
chmod 750 /var/lib/cockroach

# Use AppArmor or SELinux to restrict filesystem access
# Only allow access to specific directories

Implement network-level controls to prevent unauthorized access to Cockroachdb's file operations. Use firewall rules to restrict which hosts can trigger backup/restore operations, and consider using Cockroachdb's enterprise features for secure backup to cloud storage.

For containerized deployments, mount volumes with bind options that prevent symlink traversal:

# Docker compose with secure volume mounts
version: '3.8'
services:
  cockroachdb:
    image: cockroachdb/cockroach:latest
    volumes:
      - type: bind
        source: ./data
        target: /cockroach/cockroach-data
        bind:
          propagation: rprivate  # Prevent symlink traversal

Regularly audit your Cockroachdb configuration and scripts. middleBrick's continuous monitoring can alert you when new symlink vulnerabilities appear in your API endpoints, helping you maintain security as your database configuration evolves.