Apache Range Header DoS (CVE-2011-3192)

Apache Range Header DoS is a well-known vulnerability that affects Apache servers that support range requests. Range requests are a type of HTTP request that allows clients to request only a portion of a file or resource. This vulnerability can allow attackers to send specially crafted range requests that can consume all the available resources on the server, leading to a denial of service (DoS) attack.

In this guide, we will provide you with a step-by-step guide on how to fix this vulnerability in your web application running on Apache server.

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Step 1: Check if your server is vulnerable

The first step is to check if your server is vulnerable to the Apache Range Header DoS vulnerability. You can use the following command to check if your Apache server supports range requests:

curl -H "Range: bytes=0-10" -I <your_website_url>

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If your server is vulnerable, you will see a response similar to the following:

HTTP/1.1 206 Partial Content Date: Tue, 23 Aug 2011 12:44:33 GMT Last-Modified: Mon, 16 Aug 2010 21:45:58 GMT ETag: "2d6-48e-48a6736e5b5c0" Accept-Ranges: bytes Content-Length: 11 Content-Range: bytes 0-10/10000 Content-Type: text/plain

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If your server is not vulnerable, you will see a response similar to the following:

HTTP/1.1 200 OK Date: Tue, 23 Aug 2011 12:44:33 GMT Last-Modified: Mon, 16 Aug 2010 21:45:58 GMT ETag: "2d6-48e-48a6736e5b5c0" Accept-Ranges: bytes Content-Length: 10000 Content-Type: text/plain

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Step 2: Update your Apache server

The first step to fix this vulnerability is to update your Apache server to the latest version. The Apache Foundation has released a patch for this vulnerability, and it is recommended to update your server as soon as possible.

To update your Apache server, you can use the following commands:

sudo apt update sudo apt upgrade apache2

If you are using a different package manager, you can use the appropriate command to update your Apache server.

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Step 3: Disable Range requests

If you are unable to update your Apache server, or if you want to provide an additional layer of security, you can disable Range requests. To disable Range requests, you can add the following lines to your Apache server configuration file:

<Location /> RequestHeader unset Range </Location>

This will remove the Range header from all incoming requests to your server.

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Step 4:  Implement a Web Application Firewall (WAF)

Another way to protect your web application from the Apache Range Header DoS vulnerability is to implement a Web Application Firewall (WAF). A WAF can detect and block malicious requests before they reach your web application.

There are several WAFs available, including ModSecurity, which is an open-source WAF that can be integrated with Apache servers.

To install ModSecurity, you can use the following command:

sudo apt install libapache2-mod-security2

Once installed, you can configure ModSecurity to detect and block malicious requests.

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Conclusion

The Apache Range Header DoS vulnerability can pose a significant threat to your web application. To fix this vulnerability, you should update your Apache server to the latest version, disable Range requests, or implement a Web Application Firewall (WAF). It is recommended to take a layered approach to security and implement multiple solutions to protect your web application from different types of attacks.

In addition to the solutions mentioned above, there are a few other best practices that you can follow to improve the security of your web application running on Apache server:

1. Use secure protocols: Ensure that your web application is using secure protocols like HTTPS to encrypt communication between the server and client.
2. Use strong authentication: Implement strong authentication mechanisms like two-factor authentication (2FA) to prevent unauthorized access to your web application.
3. Regularly backup your data: Regularly backup your web application data to prevent data loss in case of a security breach or other disasters.
4. Keep your software up-to-date: Regularly update your web application, server, and other software to ensure that you are using the latest security patches.
5. Monitor your server logs: Regularly monitor your server logs to detect and respond to any suspicious activity.

By following these best practices and implementing multiple security solutions, you can significantly reduce the risk of a successful attack on your web application.

In conclusion, the Apache Range Header DoS vulnerability is a serious threat to your web application. It is essential to take immediate action to fix this vulnerability by updating your Apache server,

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