Server-Side Request Forgery (SSRF)
What is Server-Side Request Forgery (SSRF)?
Server-Side Request Forgery (SSRF) is a type of web application vulnerability that occurs when an attacker can manipulate the server-side code to make it perform unauthorized HTTP requests to other web applications. SSRF attacks can allow an attacker to send requests from the vulnerable server to internal or external network resources, which can result in data leaks, access to sensitive data or even compromise the entire network.
An SSRF attack typically involves an attacker tricking a server into making a request to a specific URL that the attacker controls. The attacker may do this by manipulating the parameters of a URL or by using other techniques to inject malicious code into the server-side code.
What is the impact of Server-Side Request Forgery (SSRF)?
Attackers can use this vulnerability to perform a variety of attacks, such as:
- Information disclosure: The attacker can use an SSRF attack to access sensitive data, such as configuration files, internal documentation or even credentials, which can be used to compromise the entire network.
- Port scanning: The attacker can use an SSRF attack to scan the network for open ports, which can be used to identify potential vulnerabilities in the system.
- Bypassing authentication and authorization: An SSRF attack can be used to bypass authentication and authorization controls by sending requests to internal services that do not enforce these controls.
- Exploiting internal APIs: An SSRF attack can be used to exploit unprotected internal APIs, which can result in unauthorized access to sensitive information or actions that the user is not authorized to perform.
- Denial-of-service (DoS): The attacker can use an SSRF attack to flood the targeted web application with requests or to perform a request to a resource that is not available, causing the application to crash or slow down.
How to prevent Server-Side Request Forgery (SSRF)?
Here are some best practices to prevent SSRF attacks:
- Use secure APIs: Use secure APIs that do not allow arbitrary URLs to be passed as parameters. This can prevent attackers from manipulating the server-side code to perform unauthorized HTTP requests.
- Input validation and sanitization: Validate and sanitize all user input, especially for URLs, to ensure that they are valid and safe. This can prevent attackers from injecting malicious URLs into the server-side code.
- Access controls: Implement access controls to limit access to only authorized users. This can prevent attackers from exploiting unprotected internal APIs or cloud infrastructure.
- Server hardening: Harden servers by removing unnecessary software and services, and limiting access to administrative interfaces. This can prevent attackers from exploiting vulnerabilities in the server-side code or gaining access to sensitive information.
- Network segmentation: Use network segmentation to prevent web applications from accessing internal resources or those that they do not need to access. This can limit the impact of an SSRF attack by preventing the attacker from accessing sensitive resources.