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Google Wallet gets prepaid security fix, but 'brute-force' issue still hangs in the air
Google says it's fixed a Wallet security flaw that potentially allowed a phone thief to spend a user's prepaid balance. The ability to provision new prepaid cards had been suspended pending the update, but has now been restored. Things aren't quite back to normal in the Big G's world of mobile money, however. Users still find themselves caught between two competing arguments over an entirely different vulnerability, which involves a 'brute-force' attack on rooted devices. Google insists that this isn't a major concern, so long as Wallet users refrain from rooting, and that the system still "offers advantages over the plastic cards and folded wallets in use today." On the other hand, the company that discovered this issue -- zvelo -- has come back at Google with an equally blunt response. It acknowledges that a handset must be rooted to be vulnerable, but crucially its researchers also say that a device doesn't have to be rooted before it's stolen. In other words, they allege that a savvy thief can potentially steal a phone and then root it themselves, and they won't be happy with Wallet until it requires longer PIN number. Whichever argument sways you, it's worth bearing in mind that there's no evidence that anyone has yet managed to exploit these weaknesses for criminal purposes.
PSA: Google Wallet vulnerable to 'brute-force' PIN attacks (update: affects rooted devices)
Security hounds over at zvelo have discovered a vulnerability in Google Wallet that means your precious PIN can be "easily revealed." Digging through the app's code and using Google's open resources to reveal its contents, they uncovered a piratical treasure trove of data: unique user IDs, Google account information, and the PIN stored as a SHA256 hex-encoded string. Since this string is known to carry four digits, it only takes a "trivial" brute-force attack involving a maximum of 10,000 calculations to decode it. To prove their point, the researchers made a Wallet Cracker app -- demoed after the break -- that does the job quicker than you can say "unexpected overdraft."Google has been receptive to these findings, but its attempts at a fix have so far been hampered by the need to coordinate with the banks, since changing the way the PIN is stored could also change which agency is responsible for its security. In the meantime, zvelo advises that there are some measures users can take themselves, aside from putting a protective hand over their pockets: refrain from rooting your phone, enable your lock screen, disable USB debugging, enable Full Disk Encryption and keep your handset up-to-date.Update: Google has responded by emphasizing that it's only users of rooted devices who are at risk. In a statement to TNW it said: "We strongly encourage people to not install Google Wallet on rooted devices and to always set up a screen lock as an additional layer of security for their phone."[Thanks to everyone who sent this in.]
