# Server-Side Request Forgery (SSRF) (CWE-918)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

**Stack:** Go

- Prevalence: Moyenne 3 langages couverts
- Impact: Élevé 4 règles de sévérité élevée
- Prevention: Documentée 4 exemples de correctifs

**OWASP:** Server-Side Request Forgery (A10:2021-Server-Side Request Forgery) - #10

## Description

By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls.

## Prevention

Stratégies de prévention pour Server-Side Request Forgery basées sur 1 règles de détection Shoulder.

### Go

Parse URL and validate host against domain allowlist

## Warning Signs

- [HIGH] user input flowing to HTTP client requests, enabling Server-Side Request Forgery attacks

## Consequences

- Lecture des données de l'application
- Contourner le mécanisme de protection
- Exécuter des commandes non autorisées

## Mitigations

- Utilisez une liste d'autorisation des destinations permises
- Désactivez les schémas d'URL inutiles (file://, gopher://)
- Utilisez une segmentation au niveau réseau

## Detection

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

## Rules by Language

### Go (1 rules)

- **Server-Side Request Forgery (SSRF)** [HIGH]: Detects user input flowing to HTTP client requests, enabling Server-Side Request Forgery attacks.
  - Remediation: Validate URLs against an allowlist of permitted domains.

```go
allowed := map[string]bool{"api.example.com": true}
parsed, _ := url.Parse(targetURL)
if !allowed[parsed.Host] {
    return errors.New("domain not allowed")
}
```

Learn more: https://shoulder.dev/learn/go/cwe-918/ssrf