# 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:** Python

- Prevalence: 보통 3개 언어 지원
- Impact: 보통 검토 권장
- Prevention: 문서화됨 4개의 수정 예시

**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

1개의 Shoulder 탐지 규칙을 기반으로 한 Open Redirect 예방 전략.

### Python

Validate redirect URLs against a domain allowlist or use relative paths

## Warning Signs

- [MEDIUM] unvalidated redirects using user input

## Consequences

- 권한 획득
- 보호 메커니즘 우회

## Mitigations

- URL은 신뢰할 수 있는 도메인의 허용 목록을 기준으로 검증하세요
- URL 매개변수를 직접 노출하기보다 매핑 체계를 사용하세요
- 외부 사이트로 리다이렉트하기 전에 경고 페이지를 표시하세요

## Detection

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

## Rules by Language

### Python (1 rules)

- **Open Redirect** [MEDIUM]: Detects unvalidated redirects using user input.
  - Remediation: Validate redirect URLs against an allowlist of permitted domains.

```python
from urllib.parse import urlparse
ALLOWED_DOMAINS = {"myapp.com"}
if urlparse(url).netloc not in ALLOWED_DOMAINS:
    url = "/"
```

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