Entries Tagged "two-factor authentication"

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Criminals are Now Exploiting SS7 Flaws to Hack Smartphone Two-Factor Authentication Systems

I’ve previously written about the serious vulnerabilities in the SS7 phone routing system. Basically, the system doesn’t authenticate messages. Now, criminals are using it to hack smartphone-based two-factor authentication systems:

In short, the issue with SS7 is that the network believes whatever you tell it. SS7 is especially used for data-roaming: when a phone user goes outside their own provider’s coverage, messages still need to get routed to them. But anyone with SS7 access, which can be purchased for around 1000 Euros according to The Süddeutsche Zeitung, can send a routing request, and the network may not authenticate where the message is coming from.

That allows the attacker to direct a target’s text messages to another device, and, in the case of the bank accounts, steal any codes needed to login or greenlight money transfers (after the hackers obtained victim passwords).

Posted on May 10, 2017 at 6:50 AM • View Comments

Iranian Phishing

CitizenLab is reporting on Iranian hacking attempts against activists, which include a real-time man-in-the-middle attack against Google’s two-factor authentication.

This report describes an elaborate phishing campaign against targets in Iran’s diaspora, and at least one Western activist. The ongoing attacks attempt to circumvent the extra protections conferred by two-factor authentication in Gmail, and rely heavily on phone-call based phishing and “real time” login attempts by the attackers. Most of the attacks begin with a phone call from a UK phone number, with attackers speaking in either English or Farsi.

The attacks point to extensive knowledge of the targets’ activities, and share infrastructure and tactics with campaigns previously linked to Iranian threat actors. We have documented a growing number of these attacks, and have received reports that we cannot confirm of targets and victims of highly similar attacks, including in Iran. The report includes extra detail to help potential targets recognize similar attacks. The report closes with some security suggestions, highlighting the importance of two-factor authentication.

The report quotes my previous writing on the vulnerabilities of two-factor authentication:

As researchers have observed for at least a decade, a range of attacks are available against 2FA. Bruce Schneier anticipated in 2005, for example, that attackers would develop real time attacks using both man-in-the-middle attacks, and attacks against devices. The”real time” phishing against 2FA that Schneier anticipated were reported at least 9 years ago.

Today, researchers regularly point out the rise of “real-time” 2FA phishing, much of it in the context of online fraud. A 2013 academic article provides a systematic overview of several of these vectors. These attacks can take the form of theft of 2FA credentials from devices (e.g. “Man in the Browser” attacks), or by using 2FA login pages. Some of the malware-based campaigns that target 2FA have been tracked for several years, are highly involved, and involve convincing targets to install separate Android apps to capture one-time passwords. Another category of these attacks works by exploiting phone number changes, SIM card registrations, and badly protected voicemail

Boing Boing article. Hacker News thread.

Posted on August 27, 2015 at 12:36 PM • View Comments

Here's How Brazilian Crooks Steal Billions

Man-in-the-middle attack against a Brazilian payment system:

Brazil has an extremely active and talented cybercrime underground, and increasingly Brazilian organized crime gangs are setting their sights on boleto users who bank online. This is typically done through malware that lies in wait until the user of the hacked PC visits their bank’s site and fills out the account information for the recipient of a boleto transaction. In this scenario, the unwitting victim submits the transfer for payment and the malware modifies the request by substituting a recipient account that the attackers control.

This is the sort of attack that bypasses any two-factor authentication system, since it occurs after all authentication has happened. A defense would be to send a confirmation notice to another device the account-owner owns, confirming the details of the transaction.

Posted on July 9, 2014 at 7:30 AM • View Comments

Twitter's Two-Factor Authentication System

Twitter just rolled out a pretty nice two-factor authentication system using your smart phone as the second factor:

The new two-factor system works like this. A user enrolls using the mobile app, which generates a 2048-bit RSA keypair. The private key lives on the phone itself, and the public key is uploaded to Twitter’s server.

When Twitter receives a new login request with a username and password, the server sends a challenge based on a 190-bit, 32 character random nonce, to the mobile app—along with a notification that gives the user the time, location, and browser information associated with the login request. The user can then opt to approve or deny this login request. If approved, the app replies to a challenge with its private key, relays that information back to the server. The server compares that challenge with a request ID, and if it authenticates, the user is automatically logged in.

On the user end, this means there’s no string of numbers to enter, nor do you have to swap to a third party authentication app or carrier. You just use the Twitter client itself. It means that the system isn’t vulnerable to a compromised SMS delivery channel, and moreover, it’s easy.

Posted on August 8, 2013 at 12:20 PM • View Comments

Bypassing Two-Factor Authentication

Yet another way two-factor authentication has been bypassed:

For a user to fall prey to Eurograbber, he or she must first be using a computer infected with the trojan. This was typically done by luring the user onto a malicious web page via a round of unfortunate web surfing or email phishing attempts. Once infected, the trojan would monitor that computer’s web browser for banking sessions. When a user visited a banking site, Eurograbber would inject JavaScript and HTML markup into their browser, prompting the user for their phone number under the guise of a “banking software security upgrade”. This is also the key to Eurograbber’s ability to bypass two-factor authentication.

It’s amazing that I wrote about this almost eight years ago. Here’s another example of the same sort of failure.

Posted on December 10, 2012 at 1:04 PM • View Comments

Man-in-the-Middle Bank Fraud Attack

This sort of attack will become more common as banks require two-factor authentication:

Tatanga checks the user account details including the number of accounts, supported currency, balance/limit details. It then chooses the account from which it could steal the highest amount.

Next, it initiates a transfer.

At this point Tatanga uses a Web Inject to trick the user into believing that the bank is performing a chipTAN test. The fake instructions request that the user generate a TAN for the purpose of this “test” and enter the TAN.

Note that the attack relies on tricking the user, which isn’t very hard.

Posted on September 14, 2012 at 11:23 AM • View Comments

The Failure of Two-Factor Authentication

In 2005, I wrote an essay called “The Failure of Two-Factor Authentication,” where I predicted that attackers would get around multi-factor authentication systems with tools that attack the transactions in real time: man-in-the-middle attacks and Trojan attacks against the client endpoint.

This BBC article describes exactly that:

After logging in to the bank’s real site, account holders are being tricked by the offer of training in a new “upgraded security system”.

Money is then moved out of the account but this is hidden from the user.

[…]

Called a Man in the Browser (MitB) attack, the malware lives in the web browser and can get between the user and the website, altering what is seen and changing details of what is being entered.

The solution is to authenticate the transaction, not the person.

EDITED TO ADD (2/6): Another link.

Posted on February 6, 2012 at 1:23 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.