HTTP request header attack and defense in Nginx reverse proxy

With the rapid development of cloud computing, big data, artificial intelligence and other fields, the scale of Internet application services is getting larger and larger, and the architecture is becoming more and more complex. Among them, Nginx reverse proxy is widely used in load balancing, security filtering, static resource distribution, cache acceleration and other occasions. However, HTTP request header attacks in Nginx reverse proxy also occur from time to time, posing a threat to the security of the application system. This article will discuss the characteristics, hazards and defensive measures of HTTP request header attacks in Nginx reverse proxy.

1. Characteristics of HTTP request header attacks

1. Tampering with the request line

The request line includes three parts: HTTP request method, URL and HTTP version. Attack An attacker can modify the request action, path name and other information by tampering with the request line, thereby tricking the server into performing illegal operations, such as database removal, injection and other attacks.

2. Modify request header fields

Request headers include Host, User-Agent, Referer, Accept, Cookie and other fields. Attackers can deceive the server by modifying request header fields. , such as disguising one's identity, bypassing security restrictions, etc.

3. Add and delete request header fields

An attacker can deceive the server by adding or deleting request header fields, including adding illegal fields, deleting required fields, etc., which may cause The application system operates abnormally or crashes.

2. The harm of HTTP request header attacks

1. Leakage of user privacy

After the attacker tamperes with the request header, the user's private information may be transmitted to Sensitive information such as user account passwords, ID numbers, etc. on other illegal servers may lead to information leakage or phishing scams.

2. Application Vulnerability Exploitation

After attackers tamper with request headers, they may exploit application vulnerabilities, such as SQL injection, XSS vulnerabilities, etc., to obtain sensitive data Or control the server.

3. Waste of resources and service failure

Attackers use HTTP request header attacks, such as frequently sending a large number of spam requests, oversized request headers, etc., which will cause server resources to be exhausted and the system to be damaged. Service interruption affects normal business operations.

3. Defense measures against HTTP request header attacks

1. Configure Nginx to limit the number of connections, limit the request size and other parameters. For requests that exceed the limit, return an error code or refuse a response.
2. Configure Nginx's HTTP module to filter and correct request headers, and use regular matching, black and white lists and other mechanisms for access control.
3. Implement WAF (Web Application Firewall) to perform security filtering on incoming HTTP requests, including request header security, request body security, etc.
4. Conduct security scans on the server regularly to discover Nginx vulnerabilities, application vulnerabilities, etc. in a timely manner and repair them in a timely manner.
5. Employee security awareness education, strengthen the security awareness of IT technicians, conduct regular security drills, and improve the ability to respond to emergencies.

To sum up, HTTP request header attack in Nginx reverse proxy is a common attack method. Attackers may exploit this vulnerability to cause security problems in the application system. We can ensure the security of the application system by limiting the number of connections, filtering request headers, using WAF, regular security scans and other defensive measures. At the same time, it is also necessary to strengthen employees’ security awareness and improve the security defense capabilities of the entire team.

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