Insufficient Logging in Echo Go with Api Keys

Insufficient logging in an Echo Go API that uses API keys creates a blind spot for security investigations. When authentication decisions and key validation are performed without writing structured audit entries, defenders lose visibility into how keys are used and whether they are being abused.

In Echo Go, a common pattern is to validate an API key in a middleware before allowing the request to proceed. If the middleware only returns a 401 or 403 without recording key identifier, timestamp, client context, and outcome, an attacker can probe keys with minimal risk of detection. For example, an attacker might iterate through known or guessed keys and the service responds with uniform error messages and no loggable audit record, enabling offline brute-force attempts without triggering alerts.

Even when logging is present, it is often insufficient when API keys are involved. Common gaps include:

• Logging the full API key value, which risks exposing sensitive secrets in logs and violates secret management best practices.
• Missing correlation of key usage to specific endpoints, making it difficult to detect anomalous patterns such as sudden spikes from a single key or usage from unexpected geolocations.
• Lack of structured fields (e.g., key ID rather than key value, request ID, user agent, IP) that would allow SIEMs to aggregate and alert effectively.

Consider an Echo Go route where a key is validated but no audit event is emitted on failure:

// Insufficient: no audit log on invalid key
func ValidateKey(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        key := c.Request().Header.Get("X-API-Key")
        if key == "" || !isValidKey(key) {
            return c.String(http.StatusUnauthorized, "unauthorized")
        }
        return next(c)
    }
}

In this scenario, a failed validation produces no record, so defenders cannot answer questions like: Which key was attempted? When did the attempts occur? Were they followed by successful requests using a valid key? Without these details, incident response relies on incomplete or absent evidence, and detection of credential stuffing or misuse is delayed.

An improved approach logs key usage without exposing the secret, includes contextual metadata, and records both successes and failures. This supports detection of patterns such as rapid successive failures from the same key (potential brute force) or usage from new clients or regions (potential credential theft). By combining structured logs with the security checks offered by a scanner like middleBrick, teams can more reliably detect and investigate issues related to authentication and exposure in their API surface.

Remediation focuses on structured, safe logging and robust key validation in Echo Go handlers. The goal is to record sufficient context to investigate abuse while protecting the actual key material.

1) Log key usage with a key identifier, not the key itself. Use a deterministic mapping (e.g., a database or cache) to translate the presented key into a non-sensitive identifier for logging.

2) Log both successes and failures with standardized fields, including timestamp, request ID, client IP, user agent, endpoint, and outcome.

3) Enforce consistent error messages to avoid leaking information via different responses for missing versus invalid keys.

Here is a concrete, safe implementation in Echo Go:

// Key represents a stored API key with an identifier
type Key struct {
    ID       string // e.g., keyID, not the secret
    Secret   string // stored securely, e.g., hashed or in a vault
    Client   string
    Scope    string
    Revoked  bool
}

// keyStore abstracts lookup; in practice this could be a DB or cache
var keyStore = map[string]*Key{ // map[secret]Key
    "abc123": {ID: "key-001", Secret: "abc123", Client: "service-a", Scope: "readwrite", Revoked: false},
}

// BySecret returns the key by secret value; in production use a constant-time compare
func BySecret(secret string) (*Key, bool) {
    k, ok := keyStore[secret]
    return k, ok
}

// ValidateKey middleware logs safe audit records
func ValidateKey(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        keyID := "unknown"
        ok := false
        secret := c.Request().Header.Get("X-API-Key")
        k, found := BySecret(secret)
        if !found || k.Revoked {
            // Log safely without exposing the secret
            auditLog(c, keyID, false, "invalid or revoked key")
            return c.String(http.StatusUnauthorized, "unauthorized")
        }
        keyID = k.ID
        ok = true
        // Record successful authentication
        auditLog(c, keyID, true, "")
        return next(c)
    }
}

// auditLog writes structured entries that can be ingested by monitoring tools
func auditLog(c echo.Context, keyID string, success bool, reason string) {
    // Example log line (use structured logging library in production)
    // Fields: time, request_id, client_ip, user_agent, endpoint, key_id, success, reason
    // Avoid logging the raw secret anywhere
    c.Logger().Infof(`{"time":"%s","request_id":"%s","client_ip":"%s","user_agent":"%s","endpoint":"%s","key_id":"%s","success":%v,"reason":"%s"}`,
        time.Now().UTC().Format(time.RFC3339),
        c.Request().Header.Get("X-Request-Id"),
        c.Request().RemoteAddr,
        c.Request().UserAgent(),
        c.Request().RequestURI,
        keyID,
        success,
        reason)
}