SSRF (Server-Side Request Forgery) is a type of security vulnerability where an attacker can make a server-side application send HTTP requests to unintended locations. This can be exploited to access internal or external resources that are otherwise inaccessible to the attacker.
- Input Manipulation: The attacker identifies an input field or parameter in the application where the server fetches a URL or resource.
- Inject Malicious URL: The attacker replaces the intended URL with a malicious one, often targeting internal services or restricted endpoints.
- Server Execution: The server executes the malicious request, potentially exposing sensitive information or interacting with other systems.Risks of SSRF
- Sensitive Data Exposure: Access to internal APIs, databases, or sensitive endpoints.
- Port Scanning: Attackers can enumerate open ports and services on internal systems.
- Bypassing Firewalls: Servers might have higher privileges to access restricted resources.
- Remote Code Execution: In some cases, SSRF can lead to code execution on the server
- Whitelist Valid URLs: Only allow URLs from trusted sources.
- Block Private IP Ranges: Disallow requests to internal/private network ranges (127.0.0.0/8, 192.168.0.0/16).
- URL Validation: Use strict URL validation and avoid user-controlled inputs.
- Timeouts and Limits: Enforce request timeouts and rate limits to prevent abuse.
- Outbound Traffic Filtering: Restrict the server's ability to make outbound requests.
By implementing these defenses, you can reduce the risk of SSRF vulnerabilities in your applications.
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