Like many of us, I follow several creators on social media to stay updated with the latest in the tech world. Among them is Tiberius, a name synonymous with web application hacking. His posts, especially those on web application security (AppSec) interview questions, are not just informative but also challenge the community to delve deeper into the subject.

The Provoking Question

Tiberius posed an intriguing question: What is the difference between web cache deception and web cache poisoning? Admittedly, I was stumped at first. But as with any good challenge, it led me down a rabbit hole of research. What I discovered was a bit anticlimactic – these are high-level/fancy terms that are used to describe low-level concepts that I was already familiar with.

Unpacking the Concepts

Let's break down these terms for better understanding:

Web Cache Deception:

• Definition: This vulnerability arises from a misconfiguration in how a web server interacts with caching mechanisms. It essentially tricks the cache into storing sensitive data that shouldn't be cached.

• Example: Consider a user accessing example.com/myprofile/picture.jpg. Here, myprofile is a dynamic, sensitive page, but the server, misled by the .jpg extension, treats it as a static resource and caches it.

• Impact: The main risk here is the unauthorized disclosure of sensitive information.

Web Cache Poisoning:

• Definition: This is a more insidious attack where an attacker intentionally inserts a malicious response into the web cache.

• How It Occurs: By exploiting vulnerabilities like unvalidated headers, the attacker prompts the server to create a harmful response, which then gets cached.

• Impact: The consequences can be dire, ranging from XSS attacks to session hijacking and phishing.

Key Differences Summarized

If you're finding all this a bit complex, here's a simpler breakdown:

1. Intent and Mechanism:

   • Web Cache Deception: Exploits a misconfiguration to expose sensitive data.

   • Web Cache Poisoning: An active attack to inject malicious content into the cache.

2. Impact:

   • Web Cache Deception: Leads to information disclosure.

   • Web Cache Poisoning: This can result in a variety of attacks, like XSS and session hijacking.

3. Attack Complexity:

   • Web Cache Deception: Simpler, exploiting server misconfigurations.

   • Web Cache Poisoning: More complex, requiring exploitation of specific application vulnerabilities.

Both Web Cache Deception and Web Cache Poisoning highlight the critical need for proper cache configuration and rigorous validation of all user inputs in web applications. These measures are essential to prevent unauthorized cache storage or manipulation, safeguarding both the application and its users.

Lab Demonstration

check out this Youtube video for a demo of both concepts

Cheers.