Integrity Failures in Echo Go with Basic Auth

An integrity failure occurs when an API allows an attacker to alter or substitute data or logic in a way the server does not expect. In Echo Go, combining Basic Authentication with integrity weaknesses typically involves predictable or missing integrity checks on authenticated requests. Basic Auth transmits credentials as base64-encoded, easily decoded values; if the server uses this transport without additional safeguards, it may expose endpoints where an authenticated user can tamper with parameters, IDs, or payloads.

When an API endpoint in Echo Go relies solely on Basic Auth for access control without verifying data integrity, it can become susceptible to tampering. For example, an authenticated user might modify a resource identifier in the URL or a JSON field to access or manipulate other users’ resources. Because Basic Auth does not inherently protect against message alteration, the server must enforce strict integrity validation—such as checking ownership, validating anti-tamper tokens, or verifying digital signatures—on each authenticated request.

Consider an endpoint that updates a user profile. If Echo Go accepts a user ID in the request body or query parameters and the Basic Auth username is used to infer permissions without re-validating that the authenticated user owns the target ID, an attacker can change the ID to escalate privileges or corrupt data. This is an integrity failure because the server trusts client-supplied identifiers rather than enforcing that the authenticated subject is authorized to operate on that specific resource. Real-world attack patterns such as ID tampering or parameter manipulation map to OWASP API Top 10 A01: Broken Object Level Authorization, and in regulated contexts they may intersect with PCI-DSS and SOC2 controls that require integrity checks on authenticated operations.

middleBrick detects integrity-related findings by correlating authentication mechanisms like Basic Auth with missing or weak authorization checks across its 12 security checks, including BOLA/IDOR and Property Authorization. In scans of Echo Go services, it flags endpoints where authenticated requests lack sufficient integrity validation, providing severity and remediation guidance. Developers should treat Basic Auth as a transport identity mechanism only and implement server-side integrity checks—such as binding requests to the authenticated subject, validating resource ownership, and rejecting unexpected or mutable identifiers—to prevent tampering.

Remediation centers on ensuring that every authenticated operation validates integrity explicitly. Do not rely on Basic Auth alone to enforce ownership or data integrity. Instead, bind the authenticated subject to the operation and verify permissions on the server for each request.

Example of a vulnerable Echo Go handler using Basic Auth without integrity checks:

package main

import (
    "net/http"
    "strings"

    "github.com/labstack/echo/v4"
)

// Vulnerable: uses Basic Auth username to infer ownership but does not validate integrity
func UpdateProfile(c echo.Context) error {
    user, pass, ok := c.Request().BasicAuth()
    if !ok {
        return c.String(http.StatusUnauthorized, "missing auth")
    }
    // Assume user is the authenticated username
    targetID := c.QueryParam("id")
    // BUG: attacker can change ?id to another user’s ID and modify it
    // No integrity check to confirm user owns targetID
    // ... update logic using targetID
    return c.String(http.StatusOK, "updated")
}

func main() {
    e := echo.New()
    e.GET("/profile", UpdateProfile)
    e.Start(":8080")
}

Fixed version with integrity and ownership validation:

package main

import (
    "errors"
    "net/http"
    "strings"

    "github.com/labstack/echo/v4"
)

// User represents a stored user record
type User struct {
    ID       string
    Username string
    // other fields
}

// fetchUserByID is a stub for a data access function
func fetchUserByID(id string) (*User, error) {
    // Replace with real data access
    if id == "current" {
        return &User{ID: "current", Username: "alice"}, nil
    }
    return nil, errors.New("not found")
}

// hasPermission checks whether the authenticated user is allowed to operate on target
func hasPermission(authenticated, target *User) bool {
    // Integrity and authorization: ensure authenticated subject owns the target
    return authenticated.ID == target.ID
}

// Secure handler: validate ownership and integrity on each request
func UpdateProfileSecure(c echo.Context) error {
    user, pass, ok := c.Request().BasicAuth()
    if !ok {
        return c.String(http.StatusUnauthorized, "missing auth")
    }
    // In practice, verify user:pass against a secure store; here we derive subject
    authenticatedUser := &User{ID: "current", Username: user}

    targetID := c.QueryParam("id")
    if targetID == "" {
        return c.String(http.StatusBadRequest, "missing id")
    }
    targetUser, err := fetchUserByID(targetID)
    if err != nil {
        return c.String(http.StatusForbidden, "access denied")
    }
    if !hasPermission(authenticatedUser, targetUser) {
        return c.String(http.StatusForbidden, "insufficient permissions")
    }
    // Integrity verified: authenticated subject matches target
    // Proceed with update using targetID safely
    return c.String(http.StatusOK, "securely updated")
}

func main() {
    e := echo.New()
    e.GET("/profile/secure", UpdateProfileSecure)
    e.Start(":8080")
}

Key remediation points:

• Always re-validate ownership on the server: do not trust client-supplied identifiers alone.
• Bind the authenticated subject to the operation by comparing identifiers or using server-side references.
• Use HTTPS to protect Basic Auth credentials in transit; treat Basic Auth as transport-level only and enforce integrity checks independently.
• For higher assurance, consider moving away from Basic Auth toward token-based mechanisms with explicit scopes and integrity tokens, and enforce strict authorization checks per request.