Brute Force Attack in Gin with Cockroachdb

A brute force attack against a Gin service using CockroachDB typically targets authentication endpoints where account lockout, rate limiting, or weak credential policies are absent. In this stack, the Gin router handles HTTP request parsing and routing, while CockroachDB serves as the distributed SQL store for user credentials and session metadata. The vulnerability arises when login or password-reset endpoints do not enforce per-identity or per-client rate limits, allowing an attacker to submit many guesses without detection.

Because CockroachDB provides strong consistency and SQL ACID guarantees, an attacker can rely on predictable query behavior and timing. If password comparisons are performed in application code rather than being pushed to the database via constant-time checks, timing differences may leak information. Additionally, if user enumeration is possible (e.g., different responses for missing users vs. incorrect passwords), an attacker can validly target existing accounts and then brute force credentials with reduced noise.

Consider a login endpoint that queries CockroachDB for a username and then compares passwords in Go:

// WARNING: Example with security weaknesses for demonstration only
rows := db.QueryRowContext(ctx, "SELECT id, password_hash FROM users WHERE username = $1", username)
var userID uuid.UUID
var passwordHash string
if err := rows.Scan(&userID, &passwordHash); err != nil {
    c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
    return
}
if !comparePasswords(passwordHash, passwordAttempt) {
    c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
    return
}

If there is no per-username or per-client rate limit, an attacker can iterate over password guesses rapidly. Because the query pattern and response times remain consistent, the attacker can infer when a username exists and when a password guess is partially correct. Without additional protections such as account lockout, exponential backoff, or multi-factor authentication, the combination of Gin’s flexible routing and CockroachDB’s reliable storage makes sustained brute force attempts feasible.

The OWASP API Security Top 10 category for Credential Stuffing/Bruteforce aligns with this risk. Identifiable patterns include non‑existent usernames receiving the same generic error, missing lockout counters, and lack of progressive delays after repeated failures. These create conditions where an attacker can methodically guess credentials without triggering defensive mechanisms.

Remediation focuses on reducing information leakage, enforcing rate limits, and using database‑side protections where possible. Below are concrete changes you can apply to a Gin service that uses CockroachDB.

1. Use constant‑time comparison and avoid early user existence hints. Always hash the provided password with the stored hash algorithm and compare in constant time, even if the user does not exist. Return a generic error message regardless of whether the username exists.

// Improved login handling
rows := db.QueryRowContext(ctx, "SELECT id, password_hash FROM users WHERE username = $1", username)
var userID uuid.UUID
var passwordHash string
err := rows.Scan(&userID, &passwordHash)
if err != nil {
    // Use a generic hash for comparison to avoid timing leaks
    dummyHash := hashPassword("dummy")
    comparePasswords(dummyHash, passwordAttempt) // constant-time dummy check
    c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
    return
}
if !comparePasswords(passwordHash, passwordAttempt) {
    c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
    return
}

2. Enforce per‑username and per‑IP rate limits using middleware before hitting CockroachDB. This reduces the effectiveness of distributed brute force attempts. Below is a simplified Gin middleware sketch that can be combined with a Redis or in‑memory store; in production you might use a token‑bucket or leaky‑bucket algorithm.

func RateLimitMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        ip := c.ClientIP()
        username := c.PostForm("username")
        key := fmt.Sprintf("rl:%s:%s", ip, username)
        // pseudo code for rate limiting logic
        if isRateLimited(key) {
            c.AbortWithStatusJSON(http.StatusTooManyRequests, gin.H{"error": "too many requests"})
            return
        }
        c.Next()
    }
}

3. Leverage CockroachDB features to enforce uniqueness and constraints that indirectly hinder brute force. For example, ensure password hashes are stored with a strong algorithm (e.g., bcrypt with appropriate cost), and consider storing failed attempt counts with a TTL to implement server‑side lockout without complex state management.

-- Example schema with constraints
CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    username STRING UNIQUE NOT NULL,
    password_hash STRING NOT NULL,
    created_at TIMESTAMPTZ DEFAULT now()
);

4. Add progressive delays after repeated failures for a given username. On each failed attempt, increment a failure counter in CockroachDB with a TTL, and use the count to increase response delay or require additional verification before allowing further attempts.

-- Increment failure counter with TTL
UPSERT INTO login_failures (username, attempts, expires_at)
VALUES ($1, 1, now() + INTERVAL '15 minutes')
ON CONFLICT (username) DO UPDATE SET attempts = login_failures.attempts + 1, expires_at = now() + INTERVAL '15 minutes';

5. Enable audit logging for authentication events to support detection and response. Record timestamp, username (or a hashed version), IP, and outcome in a separate table, and monitor for spikes that indicate ongoing brute force campaigns.

-- Audit log example
CREATE TABLE auth_audit (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    username STRING NOT NULL,
    ip INET NOT NULL,
    outcome STRING NOT NULL,
    created_at TIMESTAMPTZ DEFAULT now()
);