STE WILLIAMS

Microsoft Patent Points to Snooping

Jun
29

A new Microsoft patent points towards Skype becoming equipped for lawful interception, which could be important as the service grows up to challenge traditional telcos.

The patent was filed back in 2009, but granted last week and picked up by Computerworld. Titled “Legal Intercept”, it covers one way in which a VoIP-based communications system might enable a call to be intercepted and covertly recorded, naming Skype as one of the services to which it could be applied.

Microsoft bought Skype back in May, but only received approval for the deal in June – so hasn’t had much time to do anything with the VoIP leader. Skype is hugely successful, with 170 million registered users, but it’s been very secretive about its protocols and security, refusing interoperability and asking users to just trust in Skype for their security.

That won’t wash in the real world, and neither will denying governments the right to listen in on their citizens. Most of us accept that security forces need to occasionally tap into phone lines, hopefully with suitable judicial oversight, but Skype’s apparent reluctance to permit such taps has resulted in rumours of secret deals and government-backed attacks on the cryptography used to protect Skype calls.

The patent describes how client, or network, software can be surreptitiously alerted that incoming and/or outgoing calls are to be monitored for a specific user. Such calls are then copied (packet by packet) to the monitoring server without the user being aware. The patent suggests the interception software could be placed in a NAT or router, but also incorporated into the VoIP client itself.

India has made it clear that Skype risks being kicked out of the country unless it sorts out some sort of lawful intercept capability, and other countries will be quick to follow India’s lead. So if Microsoft wants to see Skype spreading around the world then it will need to have just what’s described in the Legal Intercept patent.

Citizens aghast that their VoIP calls could be intercepted might be annoyed, but they’d be better off petitioning their governments, rather than raging against the companies trying to obey the law.

Cellphone Snooping Now Easier & Cheaper

Jan
21

Cryptographers have devised a low-cost way to intercept phone calls and text messages sent over the majority of the world’s mobile networks.

The attack, which requires four $15 Motorola handsets, a medium-end computer and a 2TB hard drive, was demonstrated last week at the 27th annual Chaos Communication Congress in Berlin. It builds off of last year’s crack of the A5/1 encryption algorithm used to protect communications sent using GSM, or Global System for Mobile Communications, technology, which carries an estimated 80 percent of the world’s mobile traffic.

The method, cooked up by researchers Karsten Nohl and Sylvain Manaut, is a significant improvement over previous techniques, which required two USRP2 receivers and software to rapidly change radio frequencies over a spectrum of 80 channels. Equipment costs of the new attack are about $650, compared with more than $4,000 using the previous method.

“GSM is as insecure as Wi-Fi was ten years ago,” Nohl, who is chief scientist at Berlin-based Security Research Labs, told The Register. “It will be attacked by the same ‘war-driving’ script kiddies soon. Any discussion over whether the attacks available in the community are incomplete or impractical should have been put to rest with the last demonstration so that we can now start discussing how to fix the networks.”

Nohl, a cryptographer who has identified gaping holes in smart cards, cordless phones and car immobilizers designed to thwart auto thieves, was alluding to comments last year from the GSM Alliance, which claimed eavesdropping on GSM communications wasn’t practical.

Nohl has long nudged mobile operators to adopt the significantly more secure A5/3 algorithm, which still isn’t widely deployed – presumably because of the cost of upgrading a huge amount of equipment that’s already in place. He also counsels them to take several “low-hanging fruit” measures. One fix involves restricting access to the HLR, or Home Location Register, which is the database that keeps track of a handset’s location on a carrier’s network. Another suggestion is for operators to randomize message padding when encrypting communications.

GSM is the most widely used mobile phone technology. It connects more than 5 billion phones, according to the GSMA. In the US, it’s used by AT&T and T-Mobile. It’s used by all major carriers in the UK.

The revised attack uses home-brewed firmware to turn the Motorola phones into wire-tapping devices that pull conversations and text messages off of a carrier’s base station. They are connected to a PC that has access to a 2TB rainbow table used to decrypt messages protected by the decades-old A5/1 algorithm. H-online.com and Wired.com have more technical details here and here. Slides from the presentation are here.