What is Web Cache Poisoning Attack
What is Web Cache Poisoning Attack

Web content caching, performed by web servers and content delivery networks, has emerged as a critical component of the internet’s infrastructure. But now it has become very vulnerable and a medium to breach the data through Web Cache Poisoning Attack.

A significant reduction in page load time and an overall speeding up of the operation is achieved through the use of web caching.

Even though web caching can be a lifesaver for us, it is not without its own set of security flaws and vulnerabilities.

And when that vulnerable thing happens to any internet user, it is referred to as ‘Web Cache Poisoning,’ and, to be honest, it may cause a great deal of devastation on their computer system.

So, before jumping straight into the topic let’s have a look at what exactly is a Web Cache and how it works.

What is Web Caching?

As we all know, the web caching process on the internet is a very important aspect of the online community’s overall functioning and success.

When a user accesses some information or a picture for the first time on the internet, the data is stored in local storage, which is referred to as a ‘Cache,’ which allows the user to retrieve the material twice as quickly as they would on their first visit to the site.

An upper-level content delivery chain uses caching to give its users faster and more convenient visits the next time a user desires to browse their website in the same way.

Web servers, intermediate systems, and content delivery networks are all practicing the use of web cache so that they may give great search time without having to retrieve original content every time a visitor to their site arrives.

 A modern website makes use of dozens of material sources such as text, videos, links, and photographs.

And as a result, it can resist losing some people as a result of the lengthy time it takes for the website to fully load on the server. Web caching is a vital component of the internet community’s ability to accomplish this, and it is beneficial to both consumers and web content providers in doing so.

A cache layer can also help with load balancing and performance optimization, which are all important considerations.

However, as the saying goes, every good thing comes at a price, and this is true for Web Caching as well.

The disadvantage of caching is that it entails a great deal of complexity in terms of maintaining multiple intermediate copies of the content and keeping them in sync with the original one.

This will be of no benefit to clients if the most recent information is not fetched from the cache, even if the site has a fast-loading time.

What is a Cache Key and How does it Work?

A cache key is used to differentiate between cached and uncached requests by bringing different parts of the requests together and yielding a combination of header values that includes the request line.

When an HTTP request is received by a cache, the cache must determine whether the request is one that it can fulfill directly or whether the request must be forwarded to the backend server for fulfillment.

User lines and host headers are typically contained within the cache key, and any components that are not contained within the cache key are referred to as unkeyed caches.

If a cache key is requested, and if it matches the cache key that was previously requested, the cache will treat them as an exact match, for which the cache key will provide a copy of the cache response that was generated for the first request.

As long as the request does not blow out or expire, this procedure is applied to all subsequent requests containing similar cache keys.

Following our discussion of what is Web Caching and how it works, we should now discuss What is Web Cache Poisoning? What is the impact of the attack on the user? and what can be done to prevent it?

What is Web Cache Poisoning Attack?

‘Web Cache Poisoning Attack is a kind of cyber-attack in which the hacker or attacker feeds some harmful data into the web server and web cache, which in turn harms the users by redirecting them to a malicious HTTP response.’ 

When a user is subjected to web cache poisoning, he or she will be redirected to a malicious website rather than the one that was requested, putting them at significant risk of data theft and malware infection, as well as other users who are attempting to access the same page.

The susceptibility of a group of users to such harmful cyberattacks is determined by whether or not the page is popular among the group of users.

When this phenomenon occurs, and if by chance any user is affected by it, there is a greater likelihood that a worm, spyware, browser hijacking program, or any other type of malicious malware will be downloaded into the user’s system/computer from that particular source.

Attackers typically take advantage of unkeyed inputs to gain control of web caches and manipulate or harm browsers such as Mozilla Firefox. Additionally, an attacker can use web cache poisoning to attack users who are vulnerable to a variety of vulnerabilities, including:

  • Open Redirection
  • JavaScript Injection
  • Cross-Site Scripting

Web Cache Poisoning Attack Impact

Whenever a user is subjected to Web Cache Poisoning, that user becomes vulnerable to the following dangers:

  • Malware Infection
  • Data Theft
  • Risk of Multiple Attacks
  • Mass Targeting

Malware Infection

Web Browsers and the system can become vulnerable to harmful malware infection as a result of Web Cache Poisoning.

This is accomplished by redirecting the user to a fraudulent website and allowing the attackers to automatically install or download malware, even if the user has not initiated the process themselves.

Data Theft

Web cache poisoning can also result in data theft by redirecting users to some phishing websites and retrieving the user’s credit card information, personal information, and saved passwords from those websites.

Risk of multiple Attacks

Multiple attacks are a possibility because an attacker can use Web Cache Poisoning to introduce other harmful viruses and plan a large-scale attack against the user.

Mass Targeting

In addition to attacking and affecting a single user, Web Cache Poisoning has the capability of targeting large groups of users at the same time.

However, there is a catch to this risk in that mass targeting will only occur if a particular website receives more traffic at a given time, and this solely depends on the popularity of the website in question.

How to Prevent Web Cache Poisoning Attack?

The following considerations should be kept in mind to avoid the potential vulnerabilities of Web Cache Poisoning:

  • A user should make every effort to avoid using the browser’s cache and should disable it entirely. Although some websites may not function properly without a web cache, a user should always prioritize security and disable web caches completely where it appears to be feasible.
  • Admins must ensure that the HTTP response file on their server is properly configured to avoid any type of poisoning.
  • Changing the cache to static mode to avoid poisoning while using the cache is another effective method of avoiding poisoning.
  • It is recommended that web developers make use of the Param Miner Extension to investigate the suspicious installation of unkeyed inputs by any third-party components.
  • All inputs should be validated and cleared by web developers, and they should avoid incorporating inputs from HTTP request headers and cookies.
  • Preventing future risks by thoroughly inspecting any third-party components before integrating them into the website should be a top priority.
  • When excluding something from the cache key for performance reasons, trying to rewrite the request is necessary.
  • Restricting fat GET requests.
  • Client-side vulnerabilities should be patched.

Conclusion (Web Cache Poisoning Attack)

The web cache poisoning attack is basically targeting the data caching ecosystem of web servers. This form of Cyber-attack is going to make Cyber security efforts even more challenging.

We must be aware of these types of Cyber-crimes and must implement the security suggestions mentioned above.

What do you think about Web Cache Poisoning?