Case Study: Are CSRF Tokens Sufficient in Preventing CSRF Attacks?

April 1, 2025

Explore how relying on CSRF tokens as a security measure against CSRF attacks is a recommended best practice, but in some cases, they are simply not enough.

Introduction

As per the Open Web Application Security Project (OWASP), CSRF vulnerabilities are recognized as a significant threat and are historically part of their top risks. The implications of CSRF attacks are far-reaching and could lead to critical security implications, such as:

Unauthorized actions: Attackers can trick users into executing unwanted actions on websites where they're authenticated. For example, changing account settings, making purchases, or transferring funds.
Identity exploitation: The attack works by exploiting the victim's authenticated session, making the application unable to distinguish between legitimate user requests and forged ones.
Silent execution: CSRF attacks often happen without the victim's knowledge as they can be hidden in seemingly innocent links, images, or embedded content.
Privilege escalation: If the victim has administrative privileges, attackers can potentially perform high-privilege actions like creating new admin accounts.
Data theft indirectly: CSRF doesn't directly steal data in the same way as other attacks (such as XSS), but it can be used to facilitate account takeover, which then allows for data theft.
Reputation damage: For organizations, successful CSRF attacks can lead to damaged reputation and loss of customer trust.

CSRF Attacks and Tokens

A CSRF attack occurs when a malicious actor manipulates an authenticated user into performing unintended actions on a website. This is achieved by sending requests from a separate site, exploiting the user's active session. The target website, recognizing the user's authenticated state, treats the malicious request as legitimate, potentially leading to the implications outlined above.

The primary defense against CSRF attacks is the implementation of CSRF tokens.

A CSRF token is a security measure that prevents unauthorized commands from trusted users. Upon logging in, the server generates a unique, random token associated with the user's session. This token is embedded in forms or HTTP requests as a hidden field or header. When submitted, the server verifies the token against the user's session. A mismatch results in the request being rejected, which effectively protects users from malicious cross-site requests during an authenticated session.

While CSRF tokens are highly effective when implemented properly, they aren't sufficient when additional security gaps exist—such as exposure through client-side JavaScript or third-party scripts. So, while they do have their place, they should be used as just one part of a broader defense strategy.

CSRF tokens prevent what's embedded on your website from being used to connect to the server in an unauthorized way. Furthermore, third-party JavaScript on your website can indeed communicate with the server, which is why CSRF protection is important.

CSRF tokens are primarily about verifying the legitimacy of requests originating from your website to protect against malicious actions initiated from other websites. While third-party JavaScript can communicate with your server, CSRF protection is still crucial to ensure that even requests made by these scripts are not being used to perform unauthorized actions on behalf of a logged-in user.

Case Study: CSRF Token Sufficiency

As websites incorporate more third-party tracking technologies, robust CSRF attack prevention becomes paramount. This case study illustrates how a misconfigured third-party vendor exposed CSRF tokens on a major retailer's website, highlighting the risks of inadequate third-party security.

The Problem

A misconfiguration allowed a third-party pixel used by a major online retailer to access CSRF tokens and authentication tokens, which, as we noted, are critical security elements for preventing unauthorized actions. This exposure transmitted the tokens to remote third-party servers, creating a significant vulnerability that risked potential data breaches.

The Discovery

Reflectiz's automated security platform monitored the retailer's web environment and detected the third-party pixel incorrectly accessing CSRF tokens, authentication keys, and personal user information.

The Mitigation

Reflectiz provided the retailer with a detailed report outlining the misconfiguration and recommended immediate actions to prevent further access to sensitive data by the third-party pixel. Recommendations included:

Avoiding exposure of CSRF tokens in the DOM or to JavaScript unless necessary
Embedding CSRF tokens in secure headers or hidden form fields,or in cookies marked HttpOnly
Evaluating and managing third-party scripts to limit data sharing
Implementing regular security audits

Reflectiz's prompt detection and mitigation were crucial in protecting the retailer from this and further CSRF attacks and related security risks. This case emphasizes the risks posed by third-party tracking technologies and the importance of careful third-party configuration and continuous monitoring.

According to the IBM Cost of Data Breach report, a potential data breach of this nature could cost retail businesses an average of $3.9 million.

Within 30 days of implementing Reflectiz's recommendations, the retailer significantly reduced their security risk posture while maintaining secure third-party application deployment.

This case demonstrates the importance of proactive security monitoring for online retailers in preventing web attacks and maintaining customer trust. Reflectiz's approach—combining discovery, behavioral analysis, and actionable alerts—helps organizations securely manage their web environments.

A Layered Approach to Protection

Addressing CSRF vulnerabilities requires a multi-faceted approach:

Continuous Monitoring: Implement solutions that specifically monitor third-party script behavior on the client-side
Token Delivery Hardening: Embed CSRF tokens in secure headers or hidden form fields, OR in cookies marked HttpOnly.
Dynamic Token Refreshing: Implement short-lived tokens that refresh frequently to limit the window of opportunity for token theft
Contextual Validation: Beyond just checking token presence, validate the context of requests (referrer headers, user patterns, etc.)
Content Security Policy (CSP): Implement strict CSP rules to limit which domains can execute scripts and receive data

Try Reflectiz today and see for yourself how continuous monitoring enhances your overall web security posture.