How to mess up a PC running Windows 7?

Question

Ok, so for my PC class I have to find 3 hacks that would mess up the lab's PC. Me and my partner are going to mess up the PC and then another team will try to fix it. The system on it is Windows 7. Anything that would stop the normal use or render the PC useless works. The conditions:

• Can't open the case
• Can't use the registry settings (due to how big it is, it would take the other team a long time to fix)
• Needs to be fixable (meaning, nothing that would mess that bad so it would require an reinstall) within 15-30 minutes (by my teacher, preferably not by the other team :)
• Can use the administrative tools
• No downloads (PC is not even connected to a network)

Note: stuff like create a fake, unclickable desktop by taking the desktop's screenshot and setting it as a background won't work as this has been discussed already. Also creating a reboot link and putting it in the autostart programs has been discussed. But anything of this type would be great to hear.

Any suggestions?

P.S. This is really for my college class, so no harm here, just pure lab fun :)

Added after edit: First would like to thank everybody for the input, some great ideas here. To clarify some things: - I have the admin account - It needs to be done in about 15 minutes, it needs to be able to be fixed in 15-30 minutes - Can't connect it to ANY network, since it's a lab PC and the college wouldn't allow them.

@Billare, yes, our teacher is a hacker at heart :)

Oh, and by the way, I don't think we are allowed to boot from another media, or mess with the BIOS, it is a Desktop Systems Administration class, and everything needs to be done inside Windows. I'll ask and see if we're allowed, if yes, then I can use some ideas from here. Thank again to everybody. 

Edit 2: Let's try a different angle. How about disabling some non-vital services which will cause some annoyance. The main point, it needs to be a pain right from the start of using the PC, not in the long term use. Wow, my head is spinning some ideas from here, great, will let you know tonight what I used.

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Moderator note: If you suggest ways to disable/break the computer, please include information on how to fix whatever it is you're breaking as well, if it is not immediately obvious.

One-liner answers, that fail to explain how they work or what the do, will be converted to comments.

Answer 1

A few major problems for you,

• In bios disable the processors L2 cache - Machine crawls
• Windows+break-->advanced system settings --> hardware tab --> Device Manager, right click disable mouse (make sure you can get here with just your keyboard so you can undo this!)
• ctrl+alt + Arrow key - on some graphics cards this rotates the screen. (usually with no method of undoing this unless you know this shortcut)
• Make a floppy boot disc/usb Key/CD Rom, pop it in the floppy drive and ensure its set to first in the boot order in bios (bonus points for removing the hdd from boot list and creating all 3 boot discs with a different os on each so they fix one then get the next!)
• Use a partitioning tool to shrink the hdd partition to a few mb more than is currently in use
• Do the opposite and fill up available space with multiple copies of large files. Combined with a startup script to start the copies would keep the hard drive filled if they first attempted cleanup by deleting files.

And a few irritations to garnish the pc with

• If it had internet access - Open Internet Properties --> connections Tab -->Lan Settings, Check use a proxy server, set the address to 127.0.0.1 (prevents them googling for solutions :P)
• Right click on desktop - View - uncheck show desktop icons (irritating but not tough to fix)
• sticky tape on the bottom of the mouse can disrupt the laser stopping the mouse working (couple this with the major disabling of the mouse in device manager to add confusion).
• if the connectors are ps2, swap the mouse and keyboard, obvious if you're used to hardware but passes a quick glance from a noob
• In word Office button -->Word Options --> proofing --> AutoCorrect Options --> add a few entries for common words, subtlety is your friend, is --> was the --> teh etc (2k7 instructions but can be done via different route in most versions)

Reverse the steps to undo the problems and ask in comments if you have trouble!

Edit - as we may have had our beastly BIOS tricks taken from us here's a couple more windows based ones

Put the shutdown command into autoexec.bat Command syntax here (you've talked about putting similar functionality in the startup folder, so this should confuse em by doing the same thing from a different spot)

Fork bomb! Create a .bat file containing the following text and make it autorun (either call from autoexec.bat or drop the .bat in startup folder)

:s
start %0
goto s

This will spawn huge numbers of processes untill the machine grinds to a halt (The code is untested but looks viable)

Answer 2

Create a mouse cursor theme where the arrow tip is NOT at mouse position.

This should be puzzling enough.

Answer 3

Change the keyboard layout to "Dvorak" or some other obscure non-English setting. They'll probably figure it out fairly quickly but it will still be really obnoxious to fix. In advance, you can write down the key combinations needed to switch back.

Answer 4

• Adjust the Date/Time format to include a funny string, often done by viruses.

  Fix: Hard to find if you are unaware of these settings, remove the string there.

• Move the .cpl items of C:\Windows\System32 elsewhere, thus disabling any control panels.

  Fix: Search for those files, probably look by last access/modified date.

  How to make this harder: Put them in a zip file, makes it harder to find them as it is a single entry.

  Alternative fix: Run sfc /scannow, which should put those files back.

• Give them a black screen after logon by removing everyone from the permissions list, don't recursively apply this though but just change it that everyone doesn't apply to this folder anymore but still all files and subdirectories.

  Fix: Hard to know the cause, but you can simply give everyone the permission back in Safe Mode.

  Why does this happen: Because Windows often pokes your %SystemRoot% (most likely C:) and if it doesn't have permissions for that it will most likely not look further and stop instead...

Answer 5

Use left Shift + left Alt + Print Screen to turn high contrast on.

And use the same key to turn it off.

Answer 6

1. Put this as a .bat file in shell:startup

   taskkill /f /im explorer.exe

Fix: Task Manager (Ctrl+Shift+Esc), File > New Task and type in explorer.exe

Answer 7

Make the most of the "Scheduled Tasks" component in Windows. Then you can make apps randomly appear or make the system shut down seemingly without cause.

Another alternative would be to write a small script (windows 7 comes with powershell) that hides the powershell window and restricts movement of the mouse to within certain boundaries.

Here is a useful links: Hide Window. And below is a code sample for moving the mouse.

[Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
[System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point(0,0)

Answer 8

How about changing the color scheme to make text and background color the same on window titles, buttons, menus etc. It may help to select the "classic" (pre-Vista) theme first. Bonus points if you can make standard controls invisible because all their colors (foreground, text, border etc) are the same as the window background.

Answer 9

Hit them with the Ease of Access Center, which is found in the control panel.

Use the FilterKeys options disable all notification to users that it is turned on and all notification (including beeps) when keys are pressed. Use the Slow Keys setting and adjust it so the user must hold down a key for more than 0.3 seconds before a key is registered as input.

Answer 10

If you're allowed to boot off a CD or USB drive, anything is possible. Once you've cleared the admin password, you can have fun.

Per the moderator note: I think the fix for anything I've listed below is pretty self-explanatory (just do the opposite of what you did to screw the machine up), but if there's something that needs clarification, please ask in a comment.

• Depending on the machine, you might be able to change the right BIOS setting to make the CPU "overheat" and turn off. (I'm trying to think outside the box here...note that some motherboards let you set the "overheat" threshold, so you can just set it low without doing any damage. The fix would be to clear the CMOS.)
• How about putting it on the network yourself? Then you can set up a different machine to do a remote shutdown of the target machine using Windows' built-in shutdown.exe or some other utility. Set it up as a bunch of scheduled tasks or write a script that does it every couple minutes.
• If the machine doesn't have much RAM, set the pagefile to 0 MB and try to run some background processes/services that chew up all the RAM.
• Do a user account batch import to create hundreds or thousands of accounts from a file you're prepared ahead of time. Pick a few at random to do sneaky things via Scheduled Tasks (like running the shutdown command as mentioned earlier).
• Disable System File Protection, boot up to the console, and start renaming important files. (Keep track of the files you rename, so you can name them back later.)
• If the machine has a DualBIOS (i.e., when the main BIOS gets corrupted, you can boot from a backup BIOS), try updating the BIOS and shut off the machine in the middle.
• Image the machine onto an external hard drive, then install WinXP/Linux/DOS/BSD/whatever.
• Boot from a live Linux CD and use dd to copy a specific range of the hard drive's contents to a file on a USB flash drive. Now overwrite that same region on the target machine's hard drive with zeros. Fix: just dd the backup file back over the same range you just corrupted on the target machine's hard drive. (don't do this if you're not comfortable with dd)
• Install one of those tiny bluetooth adapters and use a keyboard/mouse from across the room to close windows, move the mouse, lock the terminal, execute other keyboard shortcuts, etc.
• Disable the hard disk controller in the BIOS.
• Fill up all the free space on the hard drive.

I think at least a couple of these should have the other guys scratching their heads--particularly the ones that don't require you to change anything in Windows itself. (Let's just hope they don't read SU.) :D

Answer 11

On top of setting up a script to force safe mode you can go under msconfig then Boot tab.

Set Safe Boot to Alternate Shell and check No GUI boot and Make all boot settings permanent after that under Advanced options... Set the Maximum memory to 256. Then disable the system Page File

Run msconfig at the shell prompt to undo the settings :)

Answer 12

Kobayashi Maru: If you can create a VHD and get Windows to boot from that, you can break the rest of rules (except for the bios rules) since technically you are not altering the installed copy of Windows 7.

BTW A really simple hack is to use bcdedit to screw up the boot process, after /exporting, then use /import to import it to repair...though you'd need a boot disk for repairing it.

Answer 13

Set the "User Profile Service" in Services to Disabled.

This service is responsible for loading and unloading user profiles. If this service is stopped or disabled, users will no longer be able to successfully logon or logoff, applications may have problems getting to users' data, and components registered to receive profile event notifications will not receive them.

Answer 14

Disable the page file and set everything you possibly can to start up... maybe write a login script that launches word, excel, power point what ever else you can find to launch that will take up resources. It won't break it but fixing it will take forever and be extremely annoying.

Answer 15

Here's a couple ideas.

• To augment any already proposed, which are scriptable in a BAT file, add them to AUTOEXEC.BAT. Make sure to put @ECHO OFF as the first line, and put this at the end of every command: > NUL 2>&1 This will make sure that AUTOEXEC.BAT doesn't print anything to the screen, for anyone who may be watching it run. This will also ensure that, if the troubleshooters don't catch this first, whatever bugs you put into the system via the script are restored on reboot.

• I haven't seen this one in awhile, but it's one I used to love: Some mouse drivers add a tab to the Control Panel applet for calibration and orientation. Typically, this will require you to click and drag an image in the "upwards" direction so that the mouse can get its bearings. If you have this option, click the image and drag it sideways or diagonally. Make sure you know your way around Windows with the keyboard first, of course.

Answer 16

Have this run on startup: taskkill /f /fi "PID ge 0" /im *

It will try to forcefully kill any process who's PID is greater than or equal to zero. Probably needs elevation.

Answer 17

I know you don't want a registry hack, but I had to reverse a virus that did something similar, just about bashed my head till I figured it out.

Go to the HKCR\exefile\shell\open\command key and change the (default) and IsolatedCommand keys to notepad.exe

Then every time they go to execute a program they will get a copy of notepad instead.

To fix, you can still run the programs as long as you do it as another user (unless you change those keys as well.)

Answer 18

Change the startup folder to be the windows folder. Windows will try to launch everything in there on startup, that's a pretty quick turnaround for annoying activity. Not too hard to fix, but really annoying because of the amount of stuff in there. It will also significantly slow down any attempt to get fixing started because stuff will just keep popping up.

Answer 19

Put every program in the Startup group multiple times. When they start the system it will bog down to absurd levels.

Also put them in AUTOEXEC.BAT. They'll boot in Safe Mode or something, fix Startup ... and it will still happen. Drive them crazy.

Fix by editing AUTOEXEC and the Startup Group.

Answer 20

One thing that comes to mind is disabling the Remote Procedure Call (RPC) service. I did this once on a windows 2000 machine, and evidently all "Properties" dialog windows refused to load.

The thing about this is that the only way to enable it back again was to find the service entry in the registry and change it into "automatic".

However, in windows 7 they have removed the ability to disable this service, but if you manage to remove it some other way (registry, but that wasn't allowed ), maybe removing the executable that it invokes (or the dll because it is invoked by svchost.exe) would seriously cripple the computer.

C:\Windows\system32\svchost.exe -k rpcss this is the invokation, find a way to avoid that and you're good to go.

EDIT: There is a rpcss.dll in C:\Windows\system32, if you delete that, all hell would break loose.

Answer 21

A friend of mine once accidentally associated the .lnk file extension to a specific application which has the effect of meaning no shortcuts could be opened (they would all open the application). The only way to fix this is to open a command line to run any applications. Can be fixed via HKEY_CLASSES_ROOT *.lnk setting.

This was on a Win 95 machine, not sure if its still possible on Windows 7.

Answer 22

I'm surprised no one mentioned the C:\Windows\System32\drivers\etc You can REALLY mess up someone's day by screwing with the services file or hosts file.

Try adding the line

127.0.0.1  google.com

To the hosts file. Easy to diagnose if you know about it. Not at all easy if you have no idea.

Answer 23

You could also use the NTFS alternate stream capacity to further hide programs behind programs. And also fill the HDD with empty files that are hidden in the alternate data stream. Couple this with no place for the OS to put a paging file and you've mimicked the L2 cache trick.

So you can also hide a batch script behind the control panel etc so that whenever they run the control panel that triggers a batch script that opens 100000000 explorers and kills the system. Have fun with this, there is lots of room for creativity here.

Read this on ADS

Resolution/Detection: You could use a little program called "LADS" to detect the ADS or some anti-malware stuff can detect ADS. Other than LADS it's virtually undetectable. It's one of the lessor known tools of NTFS.

You are free to just delete the stream that is attached to a named data stream. Here is a "Wikipedia" entry on ADS: http://www.wikistc.org/wiki/Alternate_data_streams

Answer 24

Change the polling rate for usb devices as described here:

http://forum.overclock3d.net/index.php?showtopic=8088

Fix: Swap back to the old backup file.

Why is this amazing? Typing will only work when done really, really slowly. Moving the mouse will seem like the sensitivity is set very low, but is instead because it just will not pick up the movement.

Answer 25

An alternative to putting the funny mayhem scripts in the startup folder (well-known) or autoexec.bat (might not work?) is to use the scheduler. There you can set things to launch periodically, when the computer boots up, after login, et cetera.

Make the task look like they belong to something already installed or windows itself, and it could be easy to overlook :)

Answer 26

Well, one of the things i can think of would be to probably rename the %system% folder to something else. Messing with the bootloader would be another possibility - you could rename c:\boot\bcd to something else, and the system won't boot.

Both should be fairly trivial to fix with a livecd and knowing what you're doing, but should keep the system from bootin

The problem is, really, most of the ways i know to 'break' a system, really breaks a system ;p

Answer 27

A couple of ideas.

1. Change the bios to not boot from any hard drive.
2. Set the screen to an incompatible monitor frequency.
3. If using USB keyboards, disable USB in the bios completely.
4. Edit boot.ini and modify the flags so that it always starts in safe mode

That last one might be rather hard to track down I suspect.

See: http://support.microsoft.com/kb/239780

I just realized this might be different under windows 7, and it is. So the windows 7 method is here: http://www.edbott.com/weblog/2008/10/the-faster-way-to-safe-mode/

You could really have some fun with this one!