The April Fools joke that might have got me fired

In high school, we had a Netware 3.12 environment, and the Guest account was enabled, albeit with very limited privileges. But for some reason, Guest could still use NET SEND, which popped up a little message in the bottom row of the destination machine's display.

The whole district shared a T1 connection to the internet. Which was more than plenty for email, but as this world-wide-web thing started gaining traction, it became quite the bottleneck. And as some of us had discovered mp3 files, the slowness simply would not do.

One day there was some severe weather and a power hiccup during school hours, and every station got a message from ADMIN informing us that the server room was running on UPS power and we should save our files and log out immediately.

Hmmmm.

A few weeks later, one of the bright sparks in the technology program realized that having everyone log off would free up some bandwidth. So he logged onto the next machine over as GUEST, and used a NET SEND ALL "SERVER ROOM POWER FAILURE - 11 MIN OF BATTERY REMAIN - SAVE FILES AND LOG OFF" and sure enough, within about a minute, the whole T1 was his. Did what he needed to do (i.e. leeching an entire fserv) for about 8 minutes, then NET SEND ALL "POWER RESTORED - RESUME YOUR WORK".

A few weeks later some hot commodity had just dropped and he repeated the drill. It still worked.

Nobody noticed that these messages came from GUEST, even the district administrator, who eventually called an electrical contractor to figure out why the power in the server room was so flaky. Someone eventually pointed it out to him, which got a very red-faced "that's really clever but please knock it off", and no further punishment. The next day, the Guest account had a lot fewer privileges.

> In high school, we had a Netware 3.12 environment, and the Guest account was enabled, albeit with very limited privileges. But for some reason, Guest could still use NET SEND, which popped up a little message in the bottom row of the destination machine's display. > ...Nobody noticed that these messages came from GUEST

You mention Netware, but as I recall the Netware function you describe was just "SEND" and "NET SEND" was a Microsoft networking thing. (But maybe there was some integration between the two after my experience with Netware, who knows.)

I mainly wanted to say, as someone who used/abused a Netware network in high school, I disassembled the SEND program and discovered that the username included in the message is not authenticated at all -- the IPX (or NETX, I forget which) software interrupt just took a string, and the SEND executable formatted the username into this string. So by crafting your own SEND program that used the software interrupt directly, you could easily forge any username you wanted. So you could very easily send a message from "ADMIN". :)

This should not be construed as a confession of any network shenanigans that may or may not have occurred at my high school. ;) :D :)