Network Security

Restrict Outbound Connections to Limit Server-Side Request Risk

Applications often need to make outbound network requests. A webhook tester may fetch a URL, an image service may download a remote image, or a document processor may retrieve an external resource. The security problem begins when an attacker can influence the destination more than the application intended. If the server can reach internal services, management endpoints, or other networks that the attacker cannot reach directly, a server-side request can cross a trust boundary on the attacker’s behalf. Validating the requested URL is important, but URL parsing, redirects, name resolution, and changing network state make application-only defenses easy to overestimate.