WEB Application Security Defense mechanism (I)

WEB programs on the internet need a large number of security mechanisms to defend against attacks. Security mechanisms mainly include: ① processing users' WEB access functions and data to prevent unauthorized access. ② Process user input to prevent the program from being affected by incorrect input.
 
 
③ Process hacker to ensure that requests can be processed normally during the attack and that hacker attacks are blocked. ④ Process the Administrator's behavior and help the Administrator configure the WEB program function. The above four points may be the direction of hacker attacks.
 
1. process user requests. Users are generally divided into unauthorized users (anonymous users), registered common users, and administrators. The permissions of each user are different, and the data and executable operations are different. WEB programs use three mechanisms to process user access: authentication, session management, and access control. These three mechanisms depend on each other and break through one point to hack into others' accounts.
 
Authentication Mechanism. Currently, most WEB programs adopt the original authentication method, that is, user name and password verification, and server verification is successful, that is, the login is successful, and the access management and access control links are taken. Some highly secure WEB programs may also be added with authentication methods such as certificates and tokens. There are many problems with the original user name and password authentication mechanism, such as obtaining User Name Information, speculating on the password, and bypassing authentication through program vulnerabilities. If the WEB program has the SQL injection vulnerability, hacker can bypass password authentication,SQL Injection Parsing.
 
After the user authentication is passed, the session management stage is started. After a user logs on, he or she will access various pages and send various http requests. At this time, the program will also process login requests from other users. In order to distinguish different users, the WEB server must assign a unique identifier to each user. Generally, a WEB program creates a session for each user and publishes a token to the user. A session is the data structure stored on the server to manage the interaction between the user and the server. A token is a unique string mapped to a session to help the WEB Program Associate requests with the user. The session token is transmitted using the hiden form field and URL query string characters. However, http cookies are generally used. If you do not have any requests within the specified time range, the server session times out and is disconnected.
 
The last step to process user requests is access control, which allows or rejects user requests according to established rules. If the previous permission authentication mechanism works normally, the server can confirm the user's identity from the user's request, and decide whether to authorize the user's request action based on the user's permission. Due to the complex requirements of access control and many scenarios, there are also many security vulnerabilities in this phase. However, during penetration testing, a large amount of repetitive work may be required to detect such vulnerabilities.
 
From: http://www.yeetrack.com /? P = 142