#10
A10:2021
Server-Side Request Forgery
SSRF flaws occur whenever a web application fetches a remote resource without validating the user-supplied URL.
Overview
New for 2021. This category represents the scenario where the security community is telling us this is important, even though it's not illustrated in the data at this time.
How Attackers Exploit This
Understanding attack patterns helps you build better defenses. These are the techniques security teams watch for.
Internal service access
Attackers use the server to make requests to internal services that are not directly accessible from the internet.
Detection signal:
Requests to internal IP ranges, localhost, or cloud metadata endpoints
Cloud metadata exploitation
In cloud environments, SSRF can access instance metadata services to obtain credentials or sensitive configuration.
Detection signal:
Requests to 169.254.169.254 or similar metadata endpoints
How to Prevent
- Segment remote resource access functionality in separate networks
- Enforce URL schema, port, and destination with a positive allowlist
- Do not send raw responses to clients
- Disable HTTP redirections
- Be aware of URL consistency to avoid DNS rebinding attacks
CWEs with Shoulder Detection (1)
These CWEs have Shoulder detection rules. Click to see specific vulnerabilities and fixes.