A Comprehensive Guide to Cross-Site Request Forgery(CSRF)

CSRF: A Brief Overview

CSRF, short for cross-site request forgery, is a web security attack that tricks and persuades users to perform actions they do not intend to. For instance, victims of CSRF might transfer funds, or change their email credentials, etc., without wanting to do so.

Hackers practicing the CSRF attack use malicious social engineering techniques to trick users into carrying out unwanted actions. A successful CSRF attack is harmful to both the users and the web app’s owner as it can have devastating aftermaths, which include:

• Hackers gaining privileges to the application
• Complete web app’s data compromise (in case of an administrative account)
• Attackers modifying application data
• Change in access and action denial like restart, exit, etc.

How Does Cross-Site Request Forgery Work?

Whenever a user tries to access a website, the browser has credentials associated with the site for easy login. These credentials hold the user’s session cookies, IP address, Windows domain credentials, and such delicate information.

The challenge is that once a user is authenticated, there is no way the site can distinguish between an authentic or forged user request. Let us explain the workings of a CSRF attack in a simple stepwise guide:

1. The victim logs into a website and gets cookies
2. The attacker creates malicious content for the victim to interact with
3. The victim is tricked into interacting with malicious content through social engineering techniques
4. The attacker uses the malicious link to send code to the website with user credentials
5. The web page accepts, and processes forged requests made by the attacker
6. The attacker eventually gains access to the page and performs unethical actions.

What are the Consequences of a CSRF Attack?

There are quite a few major consequences that a victim of a CSRF attack might have to deal with. Check out some of these top consequences that are at the most risk below.

1. Complete Account Takeover

A successfully carried out CSRF attack can give attackers full control over the user’s account, allowing them to exploit sensitive information as they wish.

2. Unauthorized Transfer of Funds

CSRF attackers might use their advantage to make fraudulent transactions from the victim’s account, wherever and however they want.

3. Change of Credentials

Credential manipulation is a common impact of a cross-site request forgery attack, as attackers can change users’ email passwords as soon as they gain unauthorized access.

Prevention Measures for Cross-site Request Forgery

Many methods and tips can help mitigate the risk of web security vulnerability through CSRF. Here are a few of the best prevention methods to follow.

• Leverage CSRF Tokens

CSRF tokens are secret cookies generated by a server-side application submitted when a user makes any request to the app. Once a request is made, the server looks for the CSRF token and denies it if the token doesn’t exist or is invalid. This keeps forged requests away.

• Same-site Cookies

Since HTML sends cookies with every request, the chances of CSRF attacks remain high. By opting for same-site cookies, you can limit the cookies sent with each request. By reducing the number of cookies sent, you also decrease the likelihood of CSRF attacks.

• Referer-based Validation Technique

The referer header in an HTTP request can be used to verify the source of every request and prevent CSRF attacks. However, even though this technique can provide a thin layer of protection, it is not as powerful a prevention option as using CSRF tokens.

• Conduct Regular Security Testing

A basic yet impactful prevention method to follow against CSRF attacks is conducting regular security testing. Make sure you are running audits and security tests frequently to ensure any existing or possible threat is identified and mitigated beforehand.