Upshot: Rather than functioning as a lock on a door, the password authentication scheme for Windows 95/98's File and Print Sharing acted more like a nail through a hasp—to open the door you only needed to pull out the nail, with hardly any effort.

Folder traversal: Total server control with a single URL
Bug identifier: MS00-078
Description: Web server folder traversal vulnerability
Alias: Directory traversal bug
Date published: Oct. 17, 2000

If there's one thing we've learned from the past decade of Microsoft patches, its that not everyone keeps on top of them. When Microsoft published this particular advisory, the patch that fixed the problem (MS00-057) had already been released two months prior.

With this bug, if you knew the layout of a Microsoft file system—which folders appear where—you could send a command to a Web server that essentially gave you total control.

As anyone who has spent any time using a Windows computer will tell you, it's not hard to find your way around the hard drive. Documents go in a particular folder path; most applications are put in another folder path; and so on.

By using dots and backslashes (or their respective unicode representations) in the URL, this bug allowed you to navigate up and down the file system and execute commands, just by knowing a few simple rules and how Windows organizes itself. While account permissions for IIS are somewhat limited, a related exploit helped escalate privileges, giving remote users the ability to do whatever they wanted to with Windows servers simply by sending a few URLs.

"Originally found as an anonymous post in the PacketStorm forums, this resulted in nearly two straight years of mass ownage against Windows web servers," Moore writes.

Upshot: Directory traversal opened up a new world for automated attacks that merely had to call a particular URL to do their dirty work.

Code Red: Deadly bug, disgusting soda
Bug identifier: MS01-033
Description: Unchecked buffer in index server ISAPI (Internet Server API) extension could enable Web server compromise
Alias: The Code Red bug
Date published: June 18, 2001

What happens when you send a ton of data at a Microsoft Web server? If it was the summer of 2001, well, you owned the network. At least that's what happened a little more than a month after Microsoft released this obscure-sounding patch for IIS Web servers.

The nature of the bug was simple: Take an IIS server, invoke a buffer overflow, and commands spill into other parts of system memory. Because the commands were issued in the context of the system itself, the bug opened up for exploitation virtually all aspects of the server's operation.