Insufficient Logging in Fiber with Api Keys

Insufficient Logging in a Fiber API that relies on Api Keys means requests are not recorded in a way that supports security analysis, incident response, or forensics. When Api Keys are used for authentication, each key represents a distinct actor that should be accountable for its actions. Without structured logs that capture the key identifier, method, path, status, and relevant metadata, an attacker can abuse a compromised key and leave little or no trace.

In practice, this often occurs when developers rely on default Fiber logging that records only basic request lines, omit the key value or a redacted representation, and do not correlate logs with authentication events. For example, if middleware validates an Api Key but the application does not emit an audit log entry when the key is presented or rejected, an attacker can iterate through valid keys or use a stolen key without the defender detecting unusual patterns. This lack of visibility prevents detection of brute-force attempts, anomalous geolocations, or unusual request rates that would otherwise trigger alerts.

Middleware that only logs successful authentication further weakens detection because failures are omitted, hiding reconnaissance behavior. Inadequate log retention or centralized aggregation also hampers investigations; events scattered across containers or functions without timestamps or request IDs make it difficult to reconstruct an attack chain. When logs do not include the key identifier (or a tokenized version), mapping suspicious activity to a specific consumer is not feasible, undermining compliance and response. Structured logs should therefore include at minimum: timestamp, request ID, HTTP method, path, status code, Api Key identifier (or a redacted token), client IP, and outcome of the authentication check.

Additionally, logging sensitive data such as full keys in plaintext is a distinct risk; logs themselves must be protected. MiddleBrick’s checks for Data Exposure and Authentication align with this topic by verifying that authentication failures and key validation events are recorded in a way that supports detection without exposing secrets. The scanner evaluates whether logs contain sufficient context to trace unauthorized usage and whether security-specific logging guidance is followed, helping teams close the gap between authentication and observability.

To remediate Insufficient Logging for Api Keys in Fiber, instrument middleware to emit structured audit logs for both successful and failed authentication attempts. Use a consistent request ID to correlate logs across services and ensure logs include the key identifier in a safe, non-reversible form (for example a hash or a tokenized reference) along with metadata needed for investigations.

Example of insecure logging — avoid this pattern where the key is omitted or only generic status is recorded:

// Inadequate: no logging of key usage or failures
app.Use(async (ctx, next) => {
    await next();
    // missing key audit
});

Improved approach with structured logging for Api Keys in Fiber:

import { Router } from 'express';
import { createHash } from 'crypto';

const apiKeyLogger = (req, res, next) => {
    const provided = req.headers['x-api-key'] || req.query.api_key;
    const keyId = provided ? createHash('sha256').update(provided).digest('hex').slice(0, 16) : 'missing';
    const requestId = req.id || req.headers['x-request-id'] || crypto.randomUUID();
    req.id = requestId;

    const start = Date.now();
    res.on('finish', () => {
        const duration = Date.now() - start;
        const logEntry = {
            timestamp: new Date().toISOString(),
            requestId,
            method: req.method,
            path: req.path,
            status: res.statusCode,
            keyId,
            clientIp: req.ip,
            outcome: res.statusCode >= 400 ? 'failure' : 'success'
        };
        // send structured log to your logging backend
        console.info(JSON.stringify(logEntry));
    });
    next();
};

app.use(apiKeyLogger);

// Example secure validation with logging hooks
app.use((req, res, next) => {
    const key = req.headers['x-api-key'];
    if (!key || !isValidKey(key)) {
        // Log failed authentication with keyId for traceability
        const keyId = key ? createHash('sha256').update(key).digest('hex').slice(0, 16) : 'missing';
        console.warn(JSON.stringify({
            timestamp: new Date().toISOString(),
            level: 'warn',
            message: 'Invalid Api Key',
            keyId,
            path: req.path,
            method: req.method,
            ip: req.ip
        }));
        return res.status(401).json({ error: 'invalid_api_key' });
    }
    // Log successful authentication with keyId
    const keyId = createHash('sha256').update(key).digest('hex').slice(0, 16);
    console.info(JSON.stringify({
        timestamp: new Date().toISOString(),
        level: 'info',
        message: 'Api Key authenticated',
        keyId,
        path: req.path,
        method: req.method,
        ip: req.ip
    }));
    next();
});