URI binding attacks and defense methods in Nginx reverse proxy

URI binding attacks and defense methods in Nginx reverse proxy

In recent years, Nginx has been widely used to host various web services, especially using the proxy module to support the reverse proxy mechanism. However, there is a common security problem in Nginx reverse proxy, namely URI binding attack. This article will introduce the cause of this problem, specific attack methods and corresponding defense methods.

What is a URI binding attack?

In web applications, URI binding refers to mapping a specific URI to a specific handler or service. In Nginx, by setting the reverse proxy configuration settings in the configuration file, a mapping relationship can be established between the URI request and the real resource address of the backend. At this point, if a hacker is able to craft a specific request that causes the proxy server to forward the request to the wrong backend server or a server with malicious code, a successful URI binding attack will occur.

Specifically, URI binding attacks can be achieved in the following ways:

1. Directly request the bound resource

Due to configuration errors or Vulnerabilities, some resources through reverse proxy are directly exposed to the Internet. At this time, hackers can directly request the resources to obtain sensitive information or conduct further attacks.

2. Construct a new URI address

Hackers can access the backend server through the proxy server by constructing a new URI address that contains malicious code or incorrect request parameters, etc. , triggering aggressive behavior.

3. Redirect attack

Hackers can construct malicious redirect links to guide users to malicious websites or phishing websites, leading to identity information leakage or other attacks.

How to defend against URI binding attacks?

1. Correctly configure reverse proxy settings

For Nginx's reverse proxy settings, correct configuration is required to ensure security. You should ensure that your proxy server is configured to only accept external requests and limit the content of URL parameters, HTTP flags, and HTTP headers in requests. No resources should be allowed to be exposed directly to the Internet.

2. Check the backend server

The backend server should be reviewed before configuring the reverse proxy to ensure that it is properly configured and secure as required . For servers that are no longer in use or have security vulnerabilities, you should consider removing them from the reverse proxy configuration.

3. Use detection tools

You can use some automated detection tools to help detect problems in the reverse proxy configuration, such as OWASP ZAP and Nmap.

4. Enhancing security policies

You can add other security policies to the proxy server, such as access control lists, intrusion detection, etc. to enhance security.

Summary

In the Nginx reverse proxy mechanism, URI binding attack is a very common security problem. The proxy server can be bypassed by constructing specific requests, causing the request to be forwarded to A faulty backend server or a server with malicious code, leading to a security breach. To prevent such attacks, administrators should ensure that reverse proxy settings are properly configured, audit backend servers, use detection tools, and harden security policies so that the reverse proxy server can maintain high performance while protecting the security of web services. .

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