NE #30: The wrong error message

This anecdote from the 1990s shows why tests are important before you let away software at the public. Part 30 of the Nerd Encyclopedia about a Strange Error Message…

In the mid-1990s, a special Internet provider started his service in the USA: WebTV Networks Incorporated. At that time, a modem was usually needed for access to the Internet, which was connected between the telephone box and the computer. WebTV worked with a set-top box and a TV, allowing access to the Internet even without a computer. The promotional slogan was:

You’re surfing the Web with a remote control in one hand and a handful of cheese puffs in the other. Now that’s progress.

On the 18th In September 1996, the company wanted to make its service available to the public. From this date it was possible to create a user account for WebTV. One day before, technicians, programming and founders sat together to check the process of user login and investigate the system for errors.

Nerd encyclopedia #30

When registering for a user, it is customary to prevent certain lewd or protected terms for the name of the account. Be it insults or reserved term such as “ admin ”, “ root” and so on. With WebTV, a file was used that contained this locked term. The file was structured as follows:

admin.* 
User names may not start with “admin”. 
postmaster 
You're not the postmaster. 
poop 
That’s a bad word. 
weenie That’s a bad word.

Each entry consisted of two lines. The first line contained a regular expression describing the unauthorized term. The second line contains the error message, someone should try to use the term for his user account. So if someone wanted to set up an account using the username admin, he was denied it with the error message “User names may not start with ’admin’.

One of the technicians had made a mistake when creating the file. He wanted to divide the file into two lists: a list of protected names (admin, postmaster, root, …) as well as a list of lewd, obscene names (fuck, poop, …). For better readability, he switched the two lists by an empty line:

admin.* User names may not start with “admin”. 
postmaster Yo u're not the postmaster.

fuck
That's a bad word.

But the empty line was also interpreted by the system as a regular expression. And this matched every input! The consequence was that the protective mechanism reacted to each name when creating a user account and the following line, as programmed, returned to the user:in the user. And in this case it was:

The wrong error message when registering for WebTV [FADD1FADD1]

The bug has of course been fixed immediately. When WebTV was made available to the public the next day, there were no insulting incidents in hear.

In any case, the incident makes it clear how important it is to test a system extensively in a protected environment.