CSRF vulnerability principle, family bucket, interview magic weapon

1. Principle of CSRF vulnerability

1. Basic principles

CSRF (Cross-site request forgery) cross-site request forgery is a method of hijacking a user's identity and performing unexpected operations in the user's name. It usually occurs after the user visits a malicious website or receives a malicious email.

The attacker uses some methods to lure the user into a malicious website, and then inserts a link or form into the site, which makes an unexpected request through the user's browser, and fakes the user's identity to perform certain operations, such as changing passwords. , transfer money, publish posts, etc.

CSRF and XSS sound similar, but the attack methods are completely different. XSS attacks use trusted sites to attack client users, while CSRF attacks trusted sites by pretending to be trusted users.

2.CSRF attack process

3.Conditions

• The user is already logged into the target website or application.
• The target website or application is not using a CSRF token to protect the request.
• An attacker is able to construct a forged request and send it to a target website or application.
• A user opens a malicious website in a browser or clicks on a malicious link, allowing an attacker to exploit the user's identity to conduct a CSRF attack.

2. CSRF vulnerability classification

1. get type

CSRF attack based on GET request: This attack uses URL parameters to initiate a GET request. By constructing a link with specific parameters, the attacker tricks the user into clicking the link and making a request to the target website while logged in.

2. Post type

CSRF attack based on POST request: This attack uses POST request to launch the attack. The attacker usually constructs a form containing malicious code and then embeds it into a web page that the victim frequently visits. When the victim has logged in to the target When the page is accessed without a website, the malicious form will automatically submit and launch an attack on the target website.

3. Harm of CSRF vulnerability

1. Change user account password or reset password.
2. Add or delete data from user accounts.
3. Post or comment under a username.
4. Make transfers or purchases as a user.
5. Install malware or viruses on a user's computer.

Therefore, a successful CSRF attack may cause serious harm to users' personal information, property security, and computer systems. To protect themselves from CSRF
attacks, users should be vigilant and not click on links from unknown sources, especially if they are already logged into a website or application. Website or application developers should also take steps to prevent
CSRF attacks, such as using technologies such as CSRF tokens to protect user data.

4. Detection

Detecting the presence of CSRF attacks usually requires black-box testing or white-box testing. The following are common testing methods and tools:

1. Manual testing:

Testers manually attempt to exploit CSRF vulnerabilities against target websites or applications to check for potential vulnerabilities.

2. Automated testing tools:

For example, OWASP ZAP (Zed Attack Proxy) and Burp Suite, these tools can automatically discover and exploit CSRF vulnerabilities to assess the security of the target website or application.

3. Security Scanner:

For example, Acunetix, Nessus, etc., these tools can conduct a comprehensive scan of the target website or application and detect security vulnerabilities, including CSRF attack vulnerabilities.

4. Vulnerability platform:

For example, HackerOne, Bugcrowd, etc., these platforms allow security researchers to submit CSRF vulnerabilities and receive corresponding rewards, thus encouraging them to discover and report potential vulnerabilities.

Regardless of the methods and tools used, detecting
the presence of CSRF attacks requires sufficient testing experience and skills to ensure that the test results are accurate, reliable, and will not cause unnecessary damage to the target website or application.

5. Prevention

Here are some common ways to protect against CSRF attacks:

1. Use CSRF token:

After the user logs in, a unique CSRF token is generated for each user, and the token is submitted to the server as a hidden field or request header information when the user initiates a POST request. The server will verify the submitted CSRF token and only accept the request and perform the corresponding operation if the token is correct. This method is called the "double submission" strategy of CSRF defense and can effectively prevent CSRF attacks.

2. Check the source site:

The server can check the source site of the request and reject the request if the source site is not the site the current user is visiting. This method requires server-side support and may reduce the user experience.

3. Avoid GET requests that use sensitive operations:

Sensitive operations, such as changing passwords, transferring funds, etc., should not use GET requests, because the parameters of GET requests can be directly exposed in the URL and can easily be exploited by attackers. Sensitive operations should be performed using POST requests or other secure methods.

4. Set the SameSite property:

The SameSite attribute can prevent cross-site request forgery attacks. It can tell the browser that only requests from the same site should be sent to the server. This can be achieved by setting the SameSite attribute in the cookie.

5. Use an anti-CSRF token:

Anti-CSRF tokens add a specific parameter to the request to indicate that the request was initiated by the user and not by a malicious website. The server will verify the validity of the parameter. If the parameter does not exist or is incorrect, the request will be considered malicious and execution will be refused.

In short, in order to prevent CSRF attacks, developers should take a variety of defensive measures, such as using CSRF tokens, setting SameSite attributes, using anti-CSRF tokens, etc., and conduct regular vulnerability scanning and security testing to ensure the security of the application.

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