Please do not use this on a network you do not own! I am not responsible for what you do with this information! This is just to demonstrate Belkin's SEVERE security flaw and it doesn't look like they're going to fix the issue.
I do not own this information. All information is from this PDF, and all credit goes to Numlock. Eftecno posted this in a comment below but it is in Italian and a bit hard to follow so I'll do an example here.
The most common SSID you will see is belkin.xxx, so I'll do an example for that. Here are the steps:
1.) Find the wlan mac address of the target router. In this case, I'll pull one from ebay (looked at the pictures): 08:86:3B:05:3A:41 I don't know how long this listing will last and I hope I don't break any rules but just to prove that this works there is the listing. Look at the shipping price, too! ;D
2.) Add 1 to the end of the mac address: 08:86:3B:05:3A:42
3.) Remove the first 2 pairs from the mac address (08:86), so you're left with 3B:05:3A:42
4.) Take the 8 characters in the mac address and rearrange them so they are in this order: 62:38:51:74. So 3B:05:3A:42 would change to AB023345.
5.) Use this conversion chart and replace the corresponding values we just calculated, AB023345.
So,Code:0123456789ABCDEF 944626378ace9bdf
The password is ce946626Code:A = c B = e 0 = 9 2 = 4 3 = 6 3 = 6 4 = 2 5 = 6
Try yours yourself now!
Also, have a look at the PDF above. There are other algorithms for other models and a few special cases for each algorithm if one doesn't work.
An online tool is availible here.
If you own a Belkin router, I HIGHLY recommend that you change the default password and SSID. Don't worry about mac address filtering or hiding your SSID, those can be easily overcome. Also, disable WPS if you can, although most of the routers feature a 3 pin max failure so if you try and fail 3 times, it locks WPS until the unit is rebooted.
Still having trouble? Have a look a BigJim's comment on page 2, his post may be able to help you out if you're stuck!
Good luck!
