# URL Redirection to Untrusted Site ('Open Redirect') (CWE-601)

A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect.

**Stack:** Go

- Prevalence: Media 3 lenguajes cubiertos
- Impact: Medio Se recomienda revisión
- Prevention: Documentada 4 ejemplos de corrección

**OWASP:** Broken Access Control (A01:2021-Broken Access Control) - #1

## Description

An open redirect vulnerability occurs when an application takes user input and uses it to redirect the user to a different URL. Attackers can exploit this to redirect users to malicious sites.

## Prevention

Estrategias de prevención para Open Redirect basadas en 1 reglas de detección de Shoulder.

### Go

Validate redirect URLs against an allowlist of trusted domains

## Warning Signs

- [MEDIUM] User input flows to redirect without validation

## Consequences

- Obtener privilegios
- Eludir mecanismo de protección

## Mitigations

- Valida las URL contra una lista de permitidos de dominios confiables
- Usa un sistema de mapeo en lugar de parámetros directos en la URL
- Muestra páginas de advertencia antes de redirigir a sitios externos

## Detection

- Total rules: 4
- Languages: go, javascript, typescript, python

## Rules by Language

### Go (1 rules)

- **Open Redirect** [MEDIUM]: User-controlled input used in http.Redirect without URL validation.
  - Remediation: Validate redirect URLs against a whitelist of allowed domains.

```go
allowed := map[string]bool{"example.com": true}
u, err := url.Parse(redirectURL)
if err != nil || !allowed[u.Host] {
    http.Error(w, "Invalid redirect", 400)
    return
}
http.Redirect(w, r, redirectURL, http.StatusFound)
```

Learn more: https://shoulder.dev/learn/go/cwe-601/open-redirect