Posts Tagged: Google Authenticator


7
Sep 16

The Limits of SMS for 2-Factor Authentication

A recent ping from a reader reminded me that I’ve been meaning to blog about the security limitations of using cell phone text messages for two-factor authentication online. The reader’s daughter had received a text message claiming to be from Google, warning that her Gmail account had been locked because someone in India had tried to access her account. The young woman was advised to expect a 6-digit verification code to be sent to her and to reply to the scammer’s message with that code.

2faMark Cobb, a computer technician in Reno, Nev., said had his daughter fallen for the ruse, her Gmail account would indeed have been completely compromised, and she really would have been locked out of her account because the crooks would have changed her password straight away.

Cobb’s daughter received the scam text message because she’d enabled 2-factor authentication on her Gmail account, selecting the option to have Google request that she enter a 6-digit code texted to her cell phone each time it detects a login from an unknown computer or location (in practice, the code is to be entered on the Gmail site, not sent in any kind of texted or emailed reply).

In this case, the thieves already had her password — most likely because she re-used it on some other site that got hacked. Cobb says he and his daughter believe her mobile number and password may have been exposed as part of the 2012 breach at LinkedIn.

In any case, the crooks were priming her to expect a code and to repeat it back to them because that code was the only thing standing in the way of their seizing control over her account. And they could control when Google would send the code to her phone because Google would do this as soon as they tried to log in using her username and password. Indeed, the timing aspect of this attack helps make it more believable to the target.

This is a fairly clever — if not novel — attack, and it’s one I’d wager would likely fool a decent percentage of users who have enabled text messages as a form of two-factor authentication. Certainly, text messaging is far from the strongest form of 2-factor authentication, but it is better than allowing a login with nothing more than a username and password, as this scam illustrates.

Nevertheless, text messaging codes to users isn’t the safest way to do two-factor authentication, even if some entities — like the U.S. Social Security Administration and Sony’s Playstation network — are just getting around to offering two-factor via SMS.

But don’t take my word for it. That’s according to the National Institute of Standards and Technology (NIST), which recently issued new proposed digital authentication guidelines urging organizations to favor other forms of two-factor — such as time-base one-time passwords generated by mobile apps — over text messaging. By the way, NIST is seeking feedback on these recommendations.

If anyone’s interested, Sophos’s Naked Security blog has a very readable breakdown of what’s new in the NIST guidelines. Among my favorite highlights is this broad directive: Favor the user.

“To begin with, make your password policies user friendly and put the burden on the verifier when possible,” Sophos’s Chester Wisniewski writes. “In other words, we need to stop asking users to do things that aren’t actually improving security.” Like expiring passwords and making users change them frequently, for example.

Okay, so the geeks-in-chief are saying it’s time to move away from texting as a form of 2-factor authentication. And, of course, they’re right, because text messages are a lot like email, in that it’s difficult to tell who really sent the message, and the message itself is sent in plain text — i.e. is readable by anyone who happens to be lurking in the middle.

But security experts and many technology enthusiasts have a tendency to think that everyone should see the world through the lens of security, whereas most mere mortal users just want to get on with their lives and are perfectly content to use the same password across multiple sites — regardless of how many times they’re told not to do so. Continue reading →


23
Nov 15

How to Enable Multifactor Security on Amazon

Amazon has added multi-factor authentication to help customers better secure their accounts from hackers. With this new feature enabled, thieves would have to know your username, password, and have access to your mobile device or impersonate you to your mobile provider in order to hijack your Amazon account. The security feature allows users to receive a one-time code via text message, automated phone call, or third-party app — such as Google Authenticator.

Step one of enabling multi-factor identification on your Amazon account.

Step one of enabling multi-factor identification on your Amazon account.

Multi-factor authentication, also often called “two-step” or “two factor” authentication, is a great way to improve the security of your various online accounts (where available). With multi-factor logins enabled, even if thieves somehow steal your account username and password they’ll still need access to the second factor — your mobile phone — to successfully hijack your account.

Users can instruct Amazon to “remember” each device, which disables future prompts for the second factor on that device going forward. If Amazon later detects a login attempt from a device it does not recognize as associated with that account, it will prompt for the code from the second factor — text message, voice call, or app (whichever you choose). Continue reading →


27
Aug 12

Dropbox Now Offers Two-Step Authentication

Online file-backup and storage service Dropbox has begun offering a two-step authentication feature to help users beef up the security of their accounts. The promised change comes less than a month after the compromise of a Dropbox employee’s account exposed many Dropbox user email addresses.

Dropbox users can take advantage of the new security measure by logging in at this link, and then clicking the “Security” tab. Under account sign in, click the link next to “Two-step verification.” You’ll have the option of getting security code sent to your mobile device, or using one of several mobile apps that leverage the Time-based One-Time Password algorithm.

If you’re already familiar with the Google Authenticator app for Gmail’s two-step verification process (available for Android/iPhone/BlackBerry) this is a no-brainer: When prompted,  open the app and create a new token, then use the app to scan the bar code on your computer screen. Enter the key generated by the app into your account settings on the site, and you’re done. Other supported apps include Amazon AWS MFA (Android) and Authenticator (Windows Phone 7).

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5
Jun 12

Attackers Hit Weak Spots in 2-Factor Authentication

An attack late last week that compromised the personal and business Gmail accounts of Matthew Prince, chief executive of Web content delivery system CloudFlare, revealed a subtle but dangerous security flaw in the 2-factor authentication process used in Google Apps for business customers. Google has since fixed the glitch, but the incident offers a timely reminder that two-factor authentication schemes are only as secure as their weakest component.

In a blog post on Friday, Prince wrote about a complicated attack in which miscreants were able to access a customer’s account on CloudFlare and change the customer’s DNS records. The attack succeeded, Prince said, in part because the perpetrators exploited a weakness in Google’s account recovery process to hijack his CloudFlare.com email address, which runs on Google Apps.

A Google spokesperson confirmed that the company “fixed a flaw that, under very specific conditions, existed in the account recovery process for Google Apps for Business customers.”

“If an administrator account that was configured to send password reset instructions to a registered secondary email address was successfully recovered, 2-step verification would have been disabled in the process,” the company said. “This could have led to abuse if their secondary email account was compromised through some other means. We resolved the issue last week to prevent further abuse.”

Prince acknowledged that the attackers also leveraged the fact that his recovery email address — his personal Gmail account — was not taking advantage of Google’s free 2-factor authentication offering. Prince claims that the final stage of the attack succeeded because the miscreants were able to trick his mobile phone provider — AT&T — into forwarding his voicemail to another account.

In a phone interview Monday, Prince said he received a phone call at 11:39 a.m. on Friday from a phone number in Chico, Calif. Not knowing anyone from that area, he let the call go to voicemail. Two minutes later, he received a voicemail that was a recorded message from Google saying that his personal Gmail account password had been changed. Prince said he then initiated the account recovery process himself and changed his password back, and that the hacker(s) and he continued to ping pong for control over the Gmail account, exchanging control 10 times in 15 minutes.

“The calls were being forwarded, because phone calls still came to me,” Prince said. “I didn’t realize my voicemail had been compromised until that evening when someone called me and soon after got a text message saying, ‘Hey, something is weird with your voicemail.'”

Gmail constantly nags users to tie a mobile phone number to their account, ostensibly so that those who forget their passwords or get locked out can have an automated, out-of-band way to receive a password reset code (Google also gets another way to link real-life identities connected to cell phone records with Gmail accounts that may not be so obviously tied to a specific identity). The default method of sending a reset code is via text message, but users can also select to receive the prompt via a phone call from Google.

The trouble is, Gmail users who haven’t availed themselves of Google’s 2-factor authentication offering (Google calls it “2-step verification”) are most likely at the mercy of the security of their mobile provider. For example, AT&T users who have not assigned a PIN to their voicemail accounts are vulnerable to outsiders listening to their voice messages, simply by spoofing the caller ID so that it matches the target’s own phone number. Prince said his AT&T PIN was a completely random 24-digit combination (and here I thought I was paranoid with a 12-digit PIN).

“Working with Google we believe we have discovered the vulnerability that allowed the hacker to access my personal Gmail account, which was what began the chain of events,” Prince wrote in an update to the blog post about the attack. “It appears to have involved a breach of AT&T’s systems that compromised the out-of-band verification. The upshot is that if an attacker knows your phone number and your phone number is listed as a possible recovery method for your Google account then, at best, your Google account may only be as secure as your voicemail PIN.”

AT&T officials did not respond to requests for comment.

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