Internet Explorer Use-After-Free Vulnerability Explained

A Microsoft Internet Explorer vulnerability has been found on March 3rd 2010 that allows attackers to run commands on users computers without their permission. In simple terms, imagine Internet Explorer is playing with a toy. In a computer program, that toy is called an object. When the browser is done with the object, it is supposed to throw it away and stop using it.

The problem with this vulnerability is that Internet Explorer could throw the object away but still keep a note pointing to where that object used to be. That note is called a pointer.

Once the object is gone, that same memory space may be reused for something else. An attacker could take advantage of this by placing malicious code where the browser still expects the old object(toy) to be. When Internet Explorer tries to use the old pointer, it can be tricked into running the attacker’s code.

This type of bug is called a use-after-free vulnerability. The program frees memory, but then tries to use it again afterward. Thankfully it only happens on older versions of internet explorer like Internet Explorer 6, 6 SP1, and 7. Updating to a new version of internet explorer would stop this specific attack from happening.

It is important to note that the attackers here do not need physical access to the computer they can get this to work simply by tricking you into navigating to a bad webpage. Doing so would allow the hackers to run code like installing malware, stealing data from the computer, or taking full control of the computer.