Insecure Direct Object Reference in Echo Go with Basic Auth

Insecure Direct Object Reference (BOLA/IDOR) occurs when an API exposes a reference to an internal object—such as a numeric user ID or a UUID—and relies solely on the caller’s identity (e.g., username) to enforce access control, rather than validating that the authenticated user is authorized to access that specific object. In Echo Go, this often manifests when a route like /users/{id} uses Basic Auth for authentication but does not ensure that the authenticated user is allowed to view or modify the resource identified by {id}.

Consider an Echo Go service that uses HTTP Basic Auth to identify a user. The handler extracts the username from the auth header and uses a path parameter userID to look up a profile record. If the lookup does not confirm that the profile’s owner matches the authenticated username, an attacker can modify userID to enumerate other users’ data. This is a BOLA/IDOR issue: authentication (via Basic Auth) is present, but authorization—verifying access to the specific object—is missing or insufficient.

In an unauthenticated scan, middleBrick tests this attack surface by attempting to access or manipulate resources using different object references while leveraging or bypassing authentication. For example, it may try /users/1 with one set of Basic Auth credentials and then /users/2 with the same or no credentials. If responses differ based on object reference and do not enforce ownership checks, middleBrick flags a BOLA/IDOR finding. This becomes especially relevant when Basic Auth is used without additional scoping, because the token (username:password) identifies the actor but does not inherently limit which objects that actor may access.

Additionally, middleBrick’s OpenAPI/Swagger analysis (2.0, 3.0, 3.1) with full $ref resolution cross-references spec definitions with runtime findings. If the spec describes a userId path parameter without clarifying ownership constraints or scopes, and runtime tests show unauthorized access is possible, the scanner correlates the design and behavior to highlight the missing authorization guard.

Real-world attack patterns tied to this issue include enumeration, data exfiltration, and horizontal privilege escalation. For instance, an attacker authenticated as a low-privilege user might iterate numeric IDs to compile a dataset belonging to other users. In more complex integrations, missing authorization checks can combine with other issues—such as insufficient rate limiting—to amplify risk. Because middleBrick tests unauthenticated attack surfaces and authenticated scenarios where credentials are supplied, it can surface BOLA/IDOR issues that purely specification-based reviews might miss.

Remediation guidance focuses on ensuring that every object access is validated against the authenticated subject. This means, for each handler that uses an object identifier, confirm that the object’s ownership or permission fields match the authenticated user’s identity or roles. Do not rely on obscurity or client-supplied indices alone; enforce checks server-side, and prefer indirect references (e.g., mapping public IDs to internal records) where feasible.

To mitigate BOLA/IDOR in Echo Go when using Basic Auth, enforce ownership checks inside each handler. Below are two concrete, working examples: one insecure pattern to avoid, and one corrected implementation that ensures the authenticated user can only access their own resource.

Insecure example to avoid

This handler authenticates via Basic Auth but does not verify that the requested userID matches the authenticated user:

// Insecure: missing ownership check
func getUser(c echo.Context) error {
    userID, err := strconv.Atoi(c.Param("id"))
    if err != nil {
        return echo.NewHTTPError(http.StatusBadRequest, "invalid user id")
    }
    user, err := store.FindUserByID(userID)
    if err != nil {
        return echo.NewHTTPError(http.StatusNotFound, "user not found")
    }
    return c.JSON(http.StatusOK, user)
}

Secure remediation with ownership validation

Authenticate via Basic Auth, then ensure the requested resource belongs to the authenticated user:

// Secure: validate that the authenticated user owns the resource
func getUser(c echo.Context) error {
    // Basic Auth credentials are available via middleware; here we retrieve them
    userAuth, ok := c.Get("userAuth").(authCredentials)
    if !ok {
        return echo.NewHTTPError(http.StatusUnauthorized, "missing credentials")
    }

    requestedID, err := strconv.Atoi(c.Param("id"))
    if err != nil {
        return echo.NewHTTPError(http.StatusBadRequest, "invalid user id")
    }

    // Enforce ownership: user can only access their own record
    if requestedID != userAuth.UserID {
        return echo.NewHTTPError(http.StatusForbidden, "access denied")
    }

    user, err := store.FindUserByID(requestedID)
    if err != nil {
        return echo.NewHTTPError(http.StatusNotFound, "user not found")
    }
    return c.JSON(http.StatusOK, user)
}

// authCredentials holds the authenticated user’s identity after Basic Auth validation
type authCredentials struct {
    Username string
    UserID   int
}

Key points in the secure version:

• Authentication is handled separately (e.g., via a Basic Auth middleware that sets userAuth on the context).
• The handler retrieves the authenticated user’s ID and compares it directly to the requested resource ID before proceeding.
• If the IDs do not match, the handler returns 403 Forbidden, preventing enumeration or unauthorized access regardless of the supplied id parameter.

Additional hardening steps include avoiding user-controlled identifiers where possible, using indirect references (e.g., mapping public tokens to internal numeric IDs), and ensuring consistent authorization logic across all endpoints that access user-specific resources. middleBrick’s scans, including its unauthenticated checks and authenticated probes with supplied credentials, can help detect whether such checks are missing in practice.