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Cold Boot Attacks on Disk Encryption
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SUMMARY
The below linked paper shows that disk encryption, the standard approach
to protecting sensitive data on laptops, can be defeated by relatively
simple methods. The paper also demonstrates the methods by using them to
defeat three popular disk encryption products: BitLocker, which comes with
Windows Vista; FileVault, which comes with MacOS X; and dm-crypt, which is
used with Linux.
DETAILS
Abstract
Contrary to popular assumption, DRAMs used in most modern computers retain
their contents for seconds to minutes after power is lost, even at
operating temperatures and even if removed from a motherboard. Although
DRAMs become less reliable when they are not refreshed, they are not
immediately erased, and their contents persist sufficiently for malicious
(or forensic) acquisition of usable full-system memory images. We show
that this phenomenon limits the ability of an operating system to protect
cryptographic key material from an attacker with physical access. We use
cold reboots to mount attacks on popular disk encryption systems
BitLocker, FileVault, dm-crypt, and TrueCrypt using no special devices
or materials. We experimentally characterize the extent and predictability
of memory remanence and report that remanence times can be increased
dramatically with simple techniques. We offer new algorithms for finding
cryptographic keys in memory images and for correcting errors caused by
bit decay. Though we discuss several strategies for partially mitigating
these risks, we know of no simple remedy that would eliminate them.
ADDITIONAL INFORMATION
The information has been provided by <mailto:jacob@appelbaum.net> Jacob
Appelbaum.
The original article can be found at:
<http://citp.princeton.edu.nyud.net/pub/coldboot.pdf>
http://citp.princeton.edu.nyud.net/pub/coldboot.pdf
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