What are the vulnerable files in PHP?

php vulnerability files include file upload vulnerabilities, SQL injection vulnerabilities, XSS vulnerabilities, etc. Detailed introduction: 1. File upload vulnerabilities refer to vulnerabilities in which attackers can execute arbitrary code or obtain system permissions by uploading malicious files. Common vulnerable files include unrestricted file upload paths, lax file type checking, and forged file names; 2. SQL injection vulnerabilities refer to attackers injecting malicious SQL statements into user-entered data to obtain, modify or delete data in the database; 3. XSS vulnerabilities, etc.

The operating system for this tutorial: Windows 10 system, PHP8.1.3 version, Dell G3 computer.

As a widely used server-side scripting language, PHP has powerful functions and flexibility, but it also has some security vulnerabilities. This article will introduce some common PHP vulnerability files and provide corresponding preventive measures to help developers improve the security of their websites.

1. File upload vulnerability

File upload vulnerability refers to a vulnerability in which an attacker can execute arbitrary code or obtain system permissions by uploading malicious files. Common vulnerable files include:

1.1 Unrestricted file upload path: In the file upload function, the upload path is not restricted, allowing attackers to upload malicious files to any directory.

1.2 Strict file type checking: Strict type checking is not performed on uploaded files, allowing attackers to upload files containing malicious code.

1.3 File name forgery: Attackers bypass the file type check and upload malicious files by forging the suffix of the file name.

Precautionary measures:

- Restrict the file upload path and only allow uploading to the specified directory.

- Perform strict type checking on uploaded files and only allow legal file types to be uploaded.

- Filter and verify file names to prevent attackers from bypassing inspections by forging file names.

2. SQL Injection Vulnerability

SQL injection vulnerability means that the attacker injects malicious SQL statements into the data entered by the user to obtain, modify or delete the data in the database. Common vulnerability files include:

2.1 User input is not filtered and verified: User input data is not filtered and verified, allowing attackers to perform arbitrary database operations by injecting malicious SQL statements.

2.2 Directly splicing SQL statements: directly splicing user-entered data and SQL statements in the code, allowing attackers to perform database operations by injecting malicious SQL statements.

Precautionary measures:

- Use prepared statements or parameterized queries to pass user-entered data as parameters to SQL statements to avoid directly splicing SQL statements.

- Filter and verify the data entered by the user to ensure that it only contains legal characters and formats.

- Use safe database operation functions, such as PDO or mysqli, to prevent SQL injection attacks.

3. XSS vulnerability

XSS vulnerability means that the attacker inserts malicious scripts into the web page, causing the user's browser to execute malicious code, thereby stealing the user's information or performing other malicious operations. Common vulnerability files include:

3.1 Failure to filter and escape user input: Failure to filter and escape user input data allows attackers to insert malicious scripts into web pages.

3.2 Directly output the data entered by the user: Directly output the data entered by the user in the web page, allowing attackers to perform malicious operations by injecting malicious scripts.

Precautionary measures:

- Filter and escape the data entered by the user to ensure that it does not contain malicious scripts.

- Use safe output functions, such as htmlspecialchars(), to escape the data entered by the user and then output it to the web page.

Conclusion:

As a widely used server-side scripting language, PHP’s security is crucial. This article introduces some common PHP vulnerability files, including file upload vulnerabilities, SQL injection vulnerabilities and XSS vulnerabilities, and provides corresponding preventive measures. Developers should improve their understanding of these vulnerabilities and take appropriate security measures to protect the security of their websites and users.

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