Posted on Di 08 April 2014

FoxBleed: Check your frequently visited websites en passant


If you have been living under a rock recently:
Heartbleed is a bug in OpenSSL that allows anyone on the internet to read chunks of memory on vulnerable servers, that may include your private data, too.

Since I also visit not-so-famous websites (whose owners might not have heard about the vulnerability) on a regular basis, I wanted to ease the checking procedure, so I could identify all vulnerable websites I'm visiting and notify those responsible.

Therefore, I quickly hacked a Firefox addon together, that may also help you during your journey of securing your Internet and as a result your private data.

You can install FoxBleed from or this server.


A new tab is opened when you visit a vulnerable site for the first time of the browser session

An unfilled heart means: This Server is probably not affected

A filled heart means: This Server is definitely affected!



This addon eases the checking procedure for the Heartblug Bug, so the user can identify all vulnerable websites he's visiting and notify those responsible.
It achieves this by automatically checking the websites you are visiting whether they are affected by the HeartBleed Vulnerability and notifies you in case they are.
The check works by uploading only the domain name to the and parsing the results.
In case you come across an affected website, you should immediately notify the website owner! Not only the website itself is exposed to danger, but also also your private data!
If you're interested in a version for Google Chrome, you can find it here:

Features - if one can even call it that:

  • when visiting a vulnerable website for the first time of the current browser session, a new tab with the corresponding is opened
  • indicates exposure to the vulnerability with a filled HeartBleed icon in the bottom right corner
  • checks each domain name only once per browser session

You can learn more about the vulnerability at "The Heartbleed Bug is a serious vulnerability in the popular OpenSSL cryptographic software library. [...] The Heartbleed bug allows anyone on the Internet to read the memory of the systems protected by the vulnerable versions of the OpenSSL software. This compromises the secret keys used to identify the service providers and to encrypt the traffic, the names and passwords of the users and the actual content. This allows attackers to eavesdrop on communications, steal data directly from the services and users and to impersonate services and users."

(cc) quickly hacked together with love by Fabian Bräunlein

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