Vodafone pooh-poohs femtocell hack claims

Vodafone has rejected claims its Sure Signal femtocells contain flaws which could allow hackers to listen in on user conversations.

Security researchers going by the name of The Hacker's Choice (THC) claimed there were some serious weaknesses with both Sure Signal's physical casing and password protections.

Femtocells, devices designed to boost 3G signal, should only be accessible to the purchase, but this was not the case with Vodafone's hardware, THC said.

"THC found a way to circumvent this and to allow any subscriber - even those not registered with the femto - to use the femto. They turned it into an IMSI [International Mobile Subscriber Identity] grabber. The attacker has to be within 50 metres range of the UK Vodafone customer to make the customer's phone use the attacker's femto," said Eduart Steiner, senior security researcher, said on the THC blog.

"The second vulnerability is that Vodafone grants the femto to the Vodafone Core Network HLR /AuC which store the secret subscriber information. This means an attacker with administrator access to the Femto can request the secret key material of a UK Vodafone mobile phone user."

The group said it could use these flaws to listen in on calls and even impersonate the victim's phone.

Vodafone said the findings related to a vulnerability in Sure Signal, which was fixed last year.

"Overnight on 12 July, a claim appeared that hackers had found security loopholes in Vodafone Sure Signal which could compromise the security of Vodafone's network. This is untrue: the Vodafone network has not been compromised," a spokesperson said.

"The claims regarding Vodafone Sure Signal, which is a signal booster used indoors, relate to a vulnerability that was detected at the start of 2010. A security patch was issued a few weeks later automatically to all Sure Signal boxes."

THC responded on its blog, saying Vodafone had still not fixed "the core of the problem," namely that "the femto transfers key material from the core network right down to the femto."

At the time of publication, Vodafone had not responded to a request for further comment.