Cross-Site Request Forgery (CSRF)

Cross-Site Request Forgery (CSRF)

Cross-Site Request Forgery (CSRF), also known as session riding, is a cybersecurity attack where a malicious website or email prompts a user to perform an unwanted action on a different site where the user is authenticated. The attack takes advantage of the user's active session with another site to execute unauthorized commands, such as transferring funds or changing settings.

Key Concepts and Definitions

CSRF is a type of security vulnerability that allows attackers to exploit the trust between a user's browser and a website they are logged into. The attacker tricks the user's browser into making a request to a different website on behalf of the user, without the user's knowledge or consent.

To execute a CSRF attack, the attacker usually sends a crafted link or email to the user. When the user clicks the link or interacts with the email, their browser sends a request to the target website, taking advantage of the user's active session and causing the target website to perform an action on behalf of the user.

The malicious website or email may contain hidden forms, images, or JavaScript code that automatically triggers actions on the target website. Since the request comes from the user's browser, the target website sees it as a legitimate request and performs the requested action, unbeknownst to the user.

How CSRF Works

1. Crafting the Attack: The attacker creates a malicious link or email that appears harmless or enticing to the user. This can include links to fake login pages or websites that mimic popular services.

2. User Interaction: The user clicks on the crafted link or interacts with the malicious email. This triggers the user's browser to send a request to the target website.

3. Active Session Exploitation: The request sent by the user's browser includes the user's session cookies or authentication credentials. The target website, seeing the request as legitimate due to the user's active session, processes the request and performs the action specified by the attacker.

4. Unwanted Action: The target website performs an action on behalf of the user, which could include changing account settings, making fraudulent transactions, or even deleting user data.

Prevention Tips

While CSRF attacks can be harmful, there are several preventive measures that users and website owners can take to mitigate the risk:

1. Web Application Firewall: Deploying a web application firewall (WAF) can help detect and filter out potential CSRF attacks. WAFs analyze incoming requests and can block suspicious or unauthorized requests.

2. Anti-CSRF Tokens: Website owners can implement anti-CSRF tokens to protect against CSRF attacks. These tokens are unique, verifiable tokens embedded in each user request. When submitting a form or making a request, the token is checked by the server to ensure it matches the expected value. If the token is missing or incorrect, the server rejects the request.

3. Log Out from Important Accounts: It is recommended to log out or use separate browser sessions when accessing important accounts or performing sensitive activities. This reduces the risk of CSRF attacks since the user's active session is not available to be exploited by malicious websites.

4. User Education: Promote user awareness and education about cybersecurity best practices. Users should be cautious when clicking on links in emails, especially if they are unfamiliar or suspicious. It is important to verify the authenticity of websites before entering login credentials or performing sensitive actions.

Examples of CSRF Attacks

1. Bank Transfer: An attacker sends a malicious link to a user, claiming it leads to a promotion or special offer. When the user clicks the link, their browser sends a request to the user's online banking website, transferring funds to the attacker's account.

2. Change of Settings: An attacker tricks a user into visiting their malicious website. The site includes hidden forms that, when submitted, modify the user's account settings on a different website, such as changing their email address or password.

3. Social Media Post: An attacker creates a website that automatically posts content on a user's social media account without their knowledge. When the user visits the malicious website, their browser triggers the post action on their authenticated social media account.

Related Terms

• Session Hijacking: Session hijacking is another type of attack where an attacker gains unauthorized access to a user's active session. By stealing the session cookies or session ID, the attacker can impersonate the user and perform actions on their behalf.

• Cross-Site Scripting (XSS): Cross-Site Scripting (XSS) is a similar attack to CSRF where malicious scripts are injected into webpages viewed by other users. XSS allows attackers to perform actions on the victim's behalf within the context of the vulnerable website.