Insufficient Logging in Fiber (Go)

Insufficient logging in a Fiber service built with Go means critical events are not recorded, making it harder to detect, investigate, and respond to security incidents. Without structured logs and context, failed authentications, authorization mismatches, and input validation errors leave minimal forensic evidence.

When using Fiber with Go, developers may rely on default or minimal logging that does not capture request identifiers, user context, or key security markers. For example, if an endpoint does not log authorization failures or sensitive data access, an attacker performing IDOR or BOLA attacks can operate without leaving traces. MiddleBrick scans detect this by correlating runtime behavior with the OpenAPI spec and flagging endpoints that lack logging for high-risk actions, such as modifying or viewing sensitive resources.

Insecure logging practices also intersect with data exposure and input validation checks. If request bodies or responses containing PII are logged in plaintext without masking, logs themselves become a data exposure vector. Fiber applications that log raw query parameters or headers without sanitization risk exposing secrets or personal information. The scanner’s Data Exposure and Input Validation checks identify endpoints where logs might inadvertently capture credentials, tokens, or sensitive payloads, especially when logs are aggregated in centralized systems without encryption or access controls.

Rate limiting and authentication checks rely on logging to provide audit trails. If Fiber routes do not log timestamps, client IPs, or authentication outcomes, it becomes difficult to identify brute force attempts or token misuse. MiddleBrick’s Authentication and Rate Limiting checks verify whether sufficient context is recorded to support incident investigation. In environments where logs are the primary source of truth for security monitoring, insufficient logging directly weakens detection capabilities and compliance reporting for frameworks such as OWASP API Top 10 and SOC2.

Compliance mappings further highlight the importance of logging in Fiber with Go. Controls in PCI-DSS, SOC2, and GDPR often require recording who accessed what, when, and with what outcome. MiddleBrick maps findings to these frameworks and flags endpoints missing audit trails for sensitive operations. By combining spec analysis with runtime tests, the scanner ensures that logging practices align with expected security behaviors, reducing the risk that incidents go unnoticed due to missing or incomplete logs.

To address insufficient logging in Fiber with Go, implement structured logging with contextual fields and ensure security-critical events are explicitly recorded. Use a dedicated logger that supports levels, request-scoped fields, and output formats that integrate with your observability stack. The following examples show how to instrument Fiber routes to capture authentication outcomes, authorization decisions, and input validation events.

Example 1: Structured logging with request context in Fiber (Go)

package main

import (
	"github.com/gofiber/fiber/v2"
	"github.com/sirupsen/logrus"
)

type loggerKey string

const requestIDKey loggerKey = "requestID"

func main() {
	app := fiber.New()
	
	// Middleware to add request ID and structured logging
	app.Use(func(c *fiber.Ctx) error {
		reqID := c.Get("X-Request-ID")
		if reqID == "" {
			reqID = "none"
		}
		c.Locals("requestID", reqID)
		logrus.WithFields(logrus.Fields{
			"request_id": reqID,
			"method":     c.Method(),
			"path":       c.Path(),
			"ip":         c.IP(),
		}).Info("request_started")
		return c.Next()
	})

	app.Get("/account/:accountID", func(c *fiber.Ctx) error {
		accountID := c.Params("accountID")
		userID := c.Locals("userID").(string)

		// Log access to sensitive resource
		logrus.WithFields(logrus.Fields{
			"request_id": c.Locals("requestID"),
			"user_id":    userID,
			"account_id": accountID,
		}).Info("account_access_attempt")

		if userID != accountID {
			logrus.WithFields(logrus.Fields{
				"request_id": c.Locals("requestID"),
				"user_id":    userID,
				"account_id": accountID,
			}).Warn("authorization_failure")
			return c.Status(fiber.StatusForbidden).SendString("access denied")
		}

		logrus.WithFields(logrus.Fields{
			"request_id": c.Locals("requestID"),
			"user_id":    userID,
			"account_id": accountID,
		}).Info("account_access_granted")
		return c.SendString("account data")
	})

	app.Listen(":3000")
}

Example 2: Masking sensitive data before logging in Fiber (Go)

package main

import (
	"github.com/gofiber/fiber/v2"
	"github.com/sirupsen/logrus"
	"strings"
)

func sanitizeLog(value string) string {
	if strings.Contains(value, "token") || strings.Contains(value, "key") {
		return "[REDACTED]"
	}
	return value
}

func main() {
	app := fiber.New()

	app.Post("/login", func(c *fiber.Ctx) error {
		body := string(c.Body())
		// Assume unmarshal into a struct in real code
		logrus.WithFields(logrus.Fields{
			"endpoint": "/login",
			"body":     sanitizeLog(body),
		}).Info("login_request")

		// Authentication logic omitted for brevity
		return c.SendString("ok")
	})

	app.Listen(":3000")
}

These examples demonstrate how to embed request identifiers, user context, and security-specific markers into logs. The first example logs authorization outcomes with sufficient detail to support incident investigation, while the second shows how to redact sensitive values before logging to avoid data exposure. MiddleBrick’s Input Validation and Data Exposure checks validate that such logging practices are in place and that logs do not introduce new risks.

For continuous assurance, use the middleBrick CLI to scan endpoints and verify that logging behaviors align with security expectations. In CI/CD, the GitHub Action can fail builds when critical logging omissions are detected, ensuring that new routes include appropriate instrumentation before deployment. The MCP Server enables these scans directly from development environments, helping maintain secure logging standards across the codebase.