How secure is your Wi-Fi network?

18 Feb 2013
Wi-Fi router

Davey Winder warns about new Wi-Fi vulnerabilities and weak wireless passwords

A recent survey by web-hosting outfit UK2 in conjunction with YouGov reveals that the British public isn’t all that "bovvered" whether or not the public Wi-Fi hotspots they connect to are encrypted, although these same folk are more likely to check that their home Wi-Fi is secured.

It obviously isn't merely a matter of security awareness but one of trust – misplaced trust in the hotel, coffee shop or pub that offers the free Wi-Fi service (or the provider behind it). It shouldn't need saying today that the WEP and WPA protocols are about as safe as Lib Dem MPs’ seats, but now it appears that the Wi-Fi Protected Setup (WPS) protocol has been well and truly compromised too.

It shouldn't need saying today that the WEP and WPA protocols are about as safe as Lib Dem MPs’ seats

"WP what?" I hear you mutter. It's just that button you probably pressed to secure your wireless router when you set it up for your home or small-business network, the one that did away with manual security configuration and made wireless security so simple and quick. Or so you believed. The truth is rather less certain, because WPS is vulnerable to attack, although not through its big red button.

PIN security

A different aspect of WPS is an eight-digit PIN you have to enter instead of pressing that button, and it’s this PIN version of the protocol that’s been shown to be much less secure than everyone had assumed.

It seems that in order to crack the encryption via standard brute-force attack, hackers don’t need to uncover all eight digits of that PIN – which would take quite a lot of time and computing resources – but have to decipher only the first four. That secure-looking PIN isn’t actually so secure after all.

Sure, your bank card employs a four-digit PIN, and both banks and customers seem happy enough to place their trust in that when placing it in an ATM, but there’s a big difference between these two seemingly identical authentication scenarios.

To take your money out of a cash machine, any would-be villain has to be both in possession of your physical card and able to guess or otherwise get hold of your PIN. To gain access to your supposedly secure wireless network, however, they don’t need physical access to your router, computer card or anything: they can just set their own computer loose on trying every possible combination.

There’s a useful "how long to crack my password" calculator – called Haystack – at the Steve Gibson GRC security site, which is accurate enough for a rough estimate, although the maths boffins will tell you that it’s far from perfect.

The trouble is, security researchers have now released a tool called Reaver that can exploit this imperfection to enable anyone to crack the more simple WPS PIN and access the clear-text version of your router’s WPA2 Pre-Shared Key (PSK), which is then revealed as a result.

The full eight-digit PIN would have more than 100 million combinations, whereas the reduced-digit PIN has only 11,000 or thereabouts. It matters not one jot how complex the PSK lying behind the PIN is, because by using the WPS method you’re in effect "protecting" your Wi-Fi network with a simple four-digit PIN.