Google Wallet is all over the headlines lately, first with its release on the Verizon network with the Galaxy Nexus and then with its release on the AT&T network with the Samsung Galaxy S II. Sprint and T-Mobile users have even been able to sideload the Google Wallet app on their respective variants of the Nexus S.

The app itself relies on the devices NFC chip to communicate with non-contact payment stations, like Mastercard’s PayPass. Google Wallet stores your credit card information allowing you to make in-store purchases with a swipe of your phone. Since the information on the chip can be accessed without direct contact several security measures were put in place to protect users.  A four digit PIN is required to make purchases with the app, adding an additional layer of security. XDA Member and zvelo employee miasma  discovered a flaw in the PIN system, allowing  retrieval of credit card information. viaForensics, a company specializing in proactive forensic security (software hacking with the goal of reporting flaws and protecting users), also helped to demonstrate the exploit, proving that the process could be repeated on other devices.

Multiple problem areas were identified but the biggest was in the encryption of the PIN. Using SHA256 hex encoding, the PIN is secured in the app data. Knowing the PIN is 4 digits, viaForensics’ calculations show a brute-force would take, at-most, calculating 10,000 SHA256 hashes. This takes little effort and both miasma and Google have been able to compromise the PIN security in private tests.

Rooted users take note; the security flaw can only be exploited on phones with root privileges. Google has acknowledged the flaw and they are working on a fix. In order to preform this attack a hacker would have to have physical access to your phone, so until a fix is published users can assure their safety by keeping their device within reach. As always, for the security of your phone, stay up to date with the latest software. Don’t forget to keep your phone secure with a lockscreen pattern, PIN or password (or face unlock if your device supports it).

To see the exploit in action, check out the video here. The original thread announcing the vulnerabilities can be found here. Google is working with the banks and card companies involved to make Google Wallet more secure and to patch this security flaw, so hopefully we’ll see some updates soon. Until then, keep those NFC enabled phones within reach at all times!