This is an interesting
one - Freezing an Android phone can help reveal its
confidential contents, German security researchers have found.
A team of researchers froze phones for an hour as
a way to get around the encryption system that protects the data on a phone by
scrambling it.
Google introduced the data scrambling system with the version
of Android known as Ice Cream Sandwich.
The attack allowed the researchers to get at contact lists,
browsing histories and photos.
Android's data scrambling system was good for end users but a
"nightmare" for law enforcement and forensics workers, the team at
Erlangen's Friedrich-Alexander University (FAU) wrote in a blogpost about their work.
To get around this, researchers Tilo Muller, Michael
Spreitzenbarth and Felix Freiling from FAU put Android phones in a freezer for
an hour until the device had cooled to below -10C.
The trio
discovered that quickly connecting and disconnecting the battery of a frozen
phone forced the handset into a vulnerable mode. This loophole let them start
it up with some custom-built software rather than its on-board Android
operating system. The researchers dubbed their custom code Frost - Forensic
Recovery of Scrambled Telephones.
The Frost software helped them copy data on a phone that
could then be analysed on a separate computer.
A chilled phone also helped their hacking project. Data fades
from memory much more slowly when chips are cold which allowed them to grab the
encryption keys and speed up unscrambling the contents of a phone.
PhD student Tilo Muller told the BBC that the attack
generally gave them access to data that had been put in memory as users browsed
websites, sent messages or shared pictures.
The researchers tested their attack against a Samsung Galaxy
Nexus handset as it was one of the first to use Android's disk encryption
system. However, they said, other phones were just as likely to be vulnerable
to the attack. The team are planning further tests on other Android handsets.
While the "cold boot" attack had been tried on
desktop PCs and laptops, Mr Muller said the trio were the first to try it on phones.
"We thought it would work because smartphones are really
small PCs," he said. "but we were quite excited that the trick with
the freezer worked so well."
The German research group is now working on defences against
the attack that ensures encryption keys are never put in vulnerable memory
chips. Instead they are only used in the memory directly attached to a phone's
processor.
