Open Redirect in Echo Go

Open Redirect vulnerabilities in Echo Go applications typically arise from improper validation of redirect URLs passed as parameters to HTTP handlers. Echo Go's flexible routing system and middleware architecture create specific attack vectors that developers must understand.

The most common pattern appears in authentication flows where Echo Go applications redirect users after login. Consider this vulnerable pattern:

func loginHandler(c echo.Context) error {
    // Authentication logic here
    return c.Redirect(http.StatusFound, c.QueryParam("next"))
}

This handler trusts the next query parameter without validation, allowing attackers to craft URLs like:

https://yourapp.com/login?next=https://evilsite.com

Echo Go's context handling makes this particularly dangerous because c.QueryParam() accepts any URL scheme. An attacker can redirect users to javascript: URLs, data: URLs, or external domains.

Another Echo Go-specific manifestation occurs in error handling middleware. When applications redirect users to error pages with query parameters:

func errorHandler(err error, c echo.Context) {
    if c.QueryParam("return_to") != "" {
        c.Redirect(http.StatusFound, c.QueryParam("return_to"))
    }
}

The middleware's access to the full request context means attackers can manipulate redirect targets across the entire application stack.

Echo Go's echo.Context interface also enables parameter injection through path parameters. A vulnerable route might look like:

e.GET("/redirect/:url", func(c echo.Context) error {
    return c.Redirect(http.StatusFound, c.Param("url"))
})

This allows direct URL injection through the path, bypassing query parameter restrictions that some WAFs might enforce.

Detecting Open Redirects in Echo Go applications requires understanding both the framework's routing patterns and common vulnerability signatures. Static analysis tools can identify risky patterns, but runtime scanning provides comprehensive coverage.

Static detection in Echo Go code should look for:

grep -r "c.Redirect(" . --include="*.go" | grep -E "(QueryParam|Param)"

This command finds redirect calls that use dynamic parameters. Look for patterns where c.Redirect() receives unvalidated input from:

• c.QueryParam() - query string parameters
• c.Param() - path parameters
• c.FormValue() - form data

Dynamic analysis with middleBrick provides Echo Go-specific scanning capabilities. The scanner identifies Open Redirect vulnerabilities by:

1. Testing common redirect parameter names: next, return_to, redirect_url, url
2. Attempting URL scheme manipulation (http, https, javascript, data)
3. Testing external domain redirection
4. Verifying if redirects preserve query parameters that could leak tokens

middleBrick's API security scanner runs these tests automatically in 5-15 seconds without requiring credentials. For Echo Go applications, it specifically checks for:

middlebrick scan https://yourechoapp.com

The scanner provides a security score (A-F) and identifies if your Echo Go application is vulnerable to Open Redirect attacks, along with remediation guidance.

Manual testing should include:

# Test with external domains
curl -s -L "https://yourapp.com/login?next=https://example.com" | grep -i location

# Test with javascript URLs
curl -s -L "https://yourapp.com/login?next=javascript:alert(1)" | grep -i location

Echo Go's middleware system means vulnerabilities might be distributed across multiple handlers, requiring comprehensive endpoint testing rather than just examining individual handlers.

Securing Echo Go applications against Open Redirect requires validation at the framework level. Echo Go provides several approaches for safe redirect handling.

The most robust solution uses a whitelist of allowed redirect targets. Echo Go's middleware system makes this straightforward:

func validateRedirect(allowed []string, next string) string {
    for _, domain := range allowed {
        if strings.HasPrefix(next, domain) {
            return next
        }
    }
    return "/" // default to home
}

func redirectHandler(c echo.Context) error {
    allowed := []string{"https://yourapp.com", "https://yourotherapp.com"}
    next := c.QueryParam("next")
    
    if next == "" {
        next = "/"
    }
    
    safeRedirect := validateRedirect(allowed, next)
    return c.Redirect(http.StatusFound, safeRedirect)
}

This approach ensures only pre-approved domains can be used for redirects. The whitelist can include internal paths and external trusted domains.

For applications requiring more dynamic redirects, Echo Go's path validation provides another layer of security:

func isSafePath(path string) bool {
    // Only allow relative paths within the application
    return !strings.Contains(path, "://") && !strings.HasPrefix(path, "/../")
}

func safeRedirect(c echo.Context) error {
    next := c.QueryParam("next")
    
    if next == "" || !isSafePath(next) {
        next = "/"
    }
    
    return c.Redirect(http.StatusFound, next)
}

This validation prevents external redirects and path traversal attacks while allowing internal navigation.

Echo Go's middleware can centralize redirect validation across the entire application:

func redirectValidatorMiddleware(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        if c.Request().URL.Query().Get("next") != "" {
            allowed := []string{"https://yourapp.com"}
            next := c.Request().URL.Query().Get("next")
            
            if !strings.HasPrefix(next, "https://yourapp.com") {
                c.Request().URL.Query().Set("next", "/")
            }
        }
        return next(c)
    }
}

// Use in application
e := echo.New()
e.Use(redirectValidatorMiddleware)

This middleware intercepts all requests and validates redirect parameters before they reach handlers, providing defense-in-depth protection.

For applications using Echo Go with authentication, combine redirect validation with session-based flow control:

func authRedirect(c echo.Context) error {
    if !isAuthenticated(c) {
        return c.Redirect(http.StatusFound, "/login")
    }
    
    next := c.QueryParam("next")
    if next != "" && isSafePath(next) {
        return c.Redirect(http.StatusFound, next)
    }
    return c.Redirect(http.StatusFound, "/dashboard")
}

This pattern ensures unauthenticated users always go to login, while authenticated users can follow safe redirects or default to a dashboard.