Insufficient Logging in Fiber with Jwt Tokens
Insufficient Logging in Fiber with Jwt Tokens — how this compromise creates or exposes risk
Insufficient Logging in a Fiber API that uses JWT tokens can weaken visibility and delay incident response. When JWT tokens are accepted but requests are not recorded with enough context, an attacker can probe endpoints, submit malformed or unsigned tokens, or attempt token replay without leaving a reliable audit trail. This lack of traceability makes it harder to detect brute-force attempts, token manipulation, or lateral movement across authenticated routes.
In a typical Fiber setup, developers may add JWT validation middleware but omit structured logging of token validation outcomes, user identities, or request metadata. Without logs that capture token issuance source (if available), scopes, expiration, and validation failures, suspicious patterns—such as repeated invalid signatures or expired tokens from the same IP—are difficult to surface. Attackers can exploit this by testing stolen or forged tokens against admin routes, knowing that failures will not be recorded or alerted.
Additionally, if logs exclude request identifiers that tie HTTP calls to specific token claims, correlating events across services becomes unreliable. For example, an endpoint that accepts a JWT with a role claim may authorize access but not log the authorization decision or the original token payload. This gap can allow privilege escalation attempts (e.g., modifying a role claim) to go unnoticed. Even when tokens are validated successfully, missing timestamps and user context reduce the usefulness of logs for forensic analysis, particularly when incidents are reviewed against frameworks like OWASP API Top 10 or common authentication weaknesses.
middleBrick can detect insufficient logging when scanning an unauthenticated Fiber endpoint that uses JWT tokens. By sending requests with missing, malformed, and valid-looking tokens, the scanner can observe whether outcomes are recorded and whether logs would support incident investigation. Findings highlight missing event details such as token validation result, user ID, scopes, request path, and correlation data, providing remediation guidance tied to authentication logging best practices.
Jwt Tokens-Specific Remediation in Fiber — concrete code fixes
To address insufficient logging in Fiber when using JWT tokens, enrich your middleware to record structured, actionable events for each request and validation outcome. Below are concrete Go examples using the Fiber framework and a JWT middleware approach that logs key details without exposing secrets.
Example 1: Structured logging for token validation outcomes
Use a middleware that validates the token and logs success or failure with relevant, non-sensitive metadata. Avoid logging the full token or private claims.
//go
package main
import (
"log"
"net/http"
"time"
"github.com/gofiber/fiber/v2"
"github.com/golang-jwt/jwt/v5"
)
type LogFields struct {
Timestamp string `json:"@timestamp"`
Method string
Path string
ClientIP string
TokenStatus string // "valid", "invalid", "missing"
UserID string // derived from claims, if available
Scopes string
ErrorCode string
ErrorMessage string
}
func jwtLogger(next fiber.Handler) fiber.Handler {
return func(c *fiber.Ctx) error {
tokenString := c.Get("Authorization")
fields := LogFields{
Timestamp: time.Now().UTC().Format(time.RFC3339),
Method: c.Method(),
Path: c.Path(),
ClientIP: c.IP(),
TokenStatus: "missing",
}
if tokenString == "" {
log.Printf("auth_event %v", fields)
return c.Status(fiber.StatusUnauthorized).JSON(fiber.Map{"error": "authorization header missing"})
}
// Remove "Bearer " prefix if present
if len(tokenString) > 7 && tokenString[:7] == "Bearer " {
tokenString = tokenString[7:]
}
claims := jwt.MapClaims{}
token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
// TODO: provide your key or validation function
return []byte("your-secret"), nil
})
if err != nil || !token.Valid {
fields.TokenStatus = "invalid"
fields.ErrorCode = "invalid_token"
fields.ErrorMessage = err.Error()
log.Printf("auth_event %v", fields)
return c.Status(fiber.StatusUnauthorized).JSON(fiber.Map{"error": "invalid token"})
}
if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
fields.TokenStatus = "valid"
if sub, ok := claims["sub"].(string); ok {
fields.UserID = sub
}
if scopes, ok := claims["scopes"].(string); ok {
fields.Scopes = scopes
}
log.Printf("auth_event %v", fields)
}
return next(c)
}
}
func main() {
app := fiber.New()
app.Use(jwtLogger)
app.Get("/api/secure", func(c *fiber.Ctx) error {
return c.JSON(fiber.Map{"message": "authorized"})
})
app.Listen(":3000")
}
Example 2: Enriching logs with request IDs and outcomes
Include a request-scoped correlation ID so you can trace a request across logs and services. Combine this with explicit outcome recording for authorization decisions.
//go
package main
import (
"context"
"log"
"net/http"
"os"
"github.com/gofiber/fiber/v2"
"github.com/golang-jwt/jwt/v5"
)
func requestID(next fiber.Handler) fiber.Handler {
return func(c *fiber.Ctx) error {
reqID := c.Get("X-Request-Id")
if reqID == "" {
reqID = "unknown"
}
c.Locals("reqID", reqID)
return next(c)
}
}
func jwtAuthWithAudit(next fiber.Handler) fiber.Handler {
return func(c *fiber.Ctx) error {
reqID := c.Locals("reqID").(string)
tokenString := c.Get("Authorization")
audit := map[string]interface{}{
"request_id": reqID,
"method": c.Method(),
"path": c.Path(),
"client_ip": c.IP(),
}
if tokenString == "" {
audit["token_status"] = "missing"
audit["error"] = "authorization header missing"
logAudit(audit)
return c.Status(fiber.StatusUnauthorized).JSON(fiber.Map{"error": "authorization header missing"})
}
if len(tokenString) > 7 && tokenString[:7] == "Bearer " {
tokenString = tokenString[7:]
}
claims := jwt.MapClaims{}
token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
return []byte("your-secret"), nil
})
if err != nil || !token.Valid {
audit["token_status"] = "invalid"
audit["error"] = err.Error()
logAudit(audit)
return c.Status(fiber.StatusUnauthorized).JSON(fiber.Map{"error": "invalid token"})
}
audit["token_status"] = "valid"
if claims != nil {
if sub, ok := claims["sub"].(string); ok {
audit["user_id"] = sub
}
if scopes, ok := claims["scopes"].(string); ok {
audit["scopes"] = scopes
}
}
logAudit(audit)
return next(c)
}
}
func logAudit(audit map[string]interface{}) {
// Send audit entry to your logging backend; keep PII and secrets out
log.Println(audit)
}
func main() {
app := fiber.New()
app.Use(requestID())
app.Use(jwtAuthWithAudit)
app.Get("/api/secure", func(c *fiber.Ctx) error {
return c.JSON(fiber.Map{"message": "authorized"})
})
app.Listen(":3000")
}
These examples show how to log token status, user ID, scopes, request identifiers, and errors in a structured way. Ensure logs are centralized and retention policies align with compliance requirements. Avoid logging raw tokens or secrets. middleBrick’s scanner can validate whether such logging is present and whether events are emitted for critical outcomes like invalid tokens or authorization denials.