Scientists circumvent the encryption used to protect smartcards
Oct. 10, 2011
On Friday, scientists have managed to circumvent the encryption used to protect smartcards that are widely used to restrict access in corporate and government buildings, and to even process payments in public transit systems, something that makes it possible to clone perfect replicas of the digital keys and steal or modify their contents, representing a critical security issue.
Developed by researchers at Germany's Ruhr University, the exploit only takes about seven hours to recover the secret key protecting the Mifare DESFire MF3ICD-40 security encryption system. And the hack doesn't even leave a single trace that the card has been compromised, but its does require equipment costing upwards of $3,000, the group said.
The contactless card, which some customers adopted following the cracking of the Mifare Classic in 2008, is used by transit agencies in San Francisco, Australia, and the Czech Republic. It was also adopted by NASA in 2004, although it's not clear if the agency has since upgraded it to a more secure system.
The findings of researchers David Oswald and Christof Paar are the latest to shatter the protection in embedded electronic devices that millions of people rely on to secure homes, offices, and mobile payment accounts.
In addition to the breaking of the Mifare Classic, a team of scientists that included Paar also managed to successfully crack the encryption of the Keeloq security system used by manufacturers of cars, garage door openers, and other similar devices.
Like the previous two hacks, the latest attack recovered the card's secret key, allowing an adversary to assume the digital identity of individuals who use it to prove they are who they say they are.
NXP has marketed the DESFire MF3ICD40 despite its growing vulnerability to attack. "It provides a recipe for how to extract the secret key material non-invasively, basically by pointing a radio probe at the card and monitoring it as it performs a transaction," said cryptographer Nate Lawson, the principal of Root Labs, who has read the research.
"This is something that's easily replicable with a few thousand dollars and a little amount of time, so it's practical," he added.
Oswald and Paar's attack relied on side-channel analysis, a technique that records a device's electromagnetic radiation or other physical characteristics to learn important clues about the encryption taking place inside.
In much the way a safe cracker listens to pin clicks to figure out a vault's combination, their differential power analysis allows them to recover the 112-bit secret key that locks digital information stored on the DESFire card.
It also involves the use of a probe connected to an oscilloscope that records electrical emanations while the card is being read by an RFID, or radio-frequency identification, reader.
For the recovery to succeed, an attacker must first buy a DESFire card and spend months making detailed and careful observations about its smallest inner behaviors. It took the researchers about a year to "profile" their card, although Oswald said that a trained engineer could probably cut that time in half.
Using the findings in their paper, a hacker could probably save even more time off the profiling. With that task out of the way, all that's required for them to compromise a card is to have physical access to it for about seven hours.
Once they're done, they will have access to the secret key needed to clone the card and access or modify whatever data is stored on it. And the hack cannot be detected later either, something that's even more troubling.
In a message to DESFire customers, Mifare representatives said the attack works only on the MF3ICD-40 model of the card, which is being discontinued at the end of 2011. They encouraged users to upgrade to the EV1 version of DESFire because it isn't susceptible as much to the attack, although that's easily debatable.
They also said that customers of the weaker model can minimize the damage of attacks by assigning unique keys for each card they deploy. When the measure is accompanied by systems that monitor card readers and a key-revocation mechanism, cards that are lost or stolen can be blacklisted, if that's any consolation.
The failure of the MF3ICD-40 is its almost complete lack of countermeasures to prevent differential power analysis. While the card skips a few random clock cycles in an attempt to misalign an attacker's traces, that countermeasure is now considered insufficient when used alone and in the context of this experiment.
Endowing the card with additional protections was considered too 'cost-prohibitive' in 2002, the year a division of Philips designed it.
Despite the growing utilization of attacks that use the technique, the company, which eventually became Netherlands-based NXP Semiconductors, continued to market the smartcard nevertheless, and was criticized at the time for its carelessness.
For now, NXP doesn't currently provide numbers on how many vulnerable cards have been purchased over the years, but earlier this year it did say it had sold over 3.5 billion smartcards globally.
NXP says that upgrading to the EV1 model is relatively painless because it is backwards-compatible with its vulnerable predecessor.
However, Lawson said the logistics of swapping out tens of thousands or even millions of cards and updating back-end systems accordingly can make the task cumbersome and very costly.
With potentially billions of cards that are still affected, companies and organizations that still rely on the card may want to seriously consider dropping them real soon for the obvious reasons this article depicts.
In other internet security news
Microsoft says that it is planning no less than eight security patches for October 11, two of them critical, as part of its regular Patch Tuesday program. The highlight of this patch is a critical update for Internet Explorer that affects all supported versions of Microsoft's web browser, including IE 9.
The second critical update covers flaws in Microsoft .NET Framework and Microsoft Silverlight that create a possible mechanism for miscreants to inject hostile code onto vulnerable systems.
The remaining six updates address lesser Windows vulnerabilities in Microsoft Forefront and Host Integration server.
All six of these updates are rated as "important" and not all of them apply to all configurations. "IT administrators will have to evaluate to what degree they affect their networks, servers and workstation," according to Wolfgang Kandek, CTO at security services firm Qualys.
As usual, more details on the security holes will emerge once Microsoft has published its patches on Tuesday.
In other internet security news
Over the past three to four years, Facebook has increasingly been the ultimate target of all kinds of nasty viruses and malware with the placement of links on its site that take you to websites infected with all kinds of malware program that will infect a visitor's computer.
Those links are placed by scammers and hackers that have nothing best to do with their time. And now the social site has recruited Websense to scan its vast social network for links to malicious sites.
Scammers are using Facebook as a means to drive traffic towards malware and exploit portals or internet scam sites. In response, Facebook has contracted with Websense for security technology that will soon analyse what's going on.
Cloud technology will assign a security classification to sites, presenting users with a warning if the location is considered dangerous.
A warning page will explain why a site might be considered malicious. Users can still proceed, but at their own risks. The approach is similar to Google Safe Browsing warning technology, which is integrated into Firefox and Chrome.
Previously, individual users had the option to add additional security filtering apps, such as Bitdefender Safego, to their profiles as a means to scan for potential spam and/or malicious links.
Facebook is now offering this type of technology by default as an extension of its previous relationship with Websense.
In other internet security news
The University of Sydney in Australia and technical publisher Elsevier said earlier this morning that they are holding their first official competitive hackathon for security students and professional software developers.
The Sydney Hackathon allows teams of up to five, a twenty-four hour time frame to develop an application to improve content delivery for scientific, technical and medical publisher Elsevier, publisher of The Lancet and SciVerse Science Direct.
"The hackathon is designed to encourage students and internet security professionals to build creative and innovative software applications for science, using data from open application program interfaces," said SUITS (Sydney Uni IT Society) president James Alexander.
The inaugural Sydney Hackathon is being held this weekend, and will offer cash prizes of up to $1500 AU to the winning team. What's more, competitors can even retain the official ownership of any intellectual property developed during the event.
Entrants have from 2.00 PM Saturday to develop an application of any kind as long as it's from Elsevier’s SciVerse and ScienceDirect platforms, which include over 10 million scientific publications from 2600 journals.
Application developers and security software designers, students from any University in Australia or full time programmers are invited to enter the hackathon.
Source: Germany's Ruhr University.
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