ARM Security Technology Building a Secure System using ...

Introduction
Lab attack
1.3.4 Who attacks devices?
The lab attack vector is the most comprehensive and invasive. If the attacker has access
to laboratory equipment, such as electron microscopes, they can perform unlimited
reverse engineering of the device. It must be assumed that the attacker can reverse
engineer transistor-level detail for any sensitive part of the design - including logic and
memories.
Attackers can reverse engineer a design, attach microscopic logic probes to silicon
metal layers, and glitch a running circuit using lasers or other techniques. Attackers can
also monitor analog signals, such as device power usage and electromagnetic emissions,
to perform attacks such as cryptographic key analysis.
In most cases, considering the rule of thumb that states every device can be broken, a
device should not try and defend against lab attack directly, but should take measures
which limit the damage when a device is broken and therefore make the lab attack
uneconomical. Use of per-device unique secrets is one example where reverse
engineering a single device provides the attacker with no useful information; they have
the secret for the device that they already own, but not any of the other devices in that
class.
Note
TrustZone technology is designed to provide a hardware-enforced logical separation
between security components and the rest of the SoC infrastructure.
Lab attacks are outside of the scope of the protection provided TrustZone technology,
although a SoC using TrustZone can be used in conjunction with an ARM SecurCore ©
smartcard if protection against physical attacks is needed for some assets.
Once a designer has identified the assets, and the possible attacks, it is important to
identify the possible attackers. Different attackers can deploy different types of attack,
and certain assets will only attract certain attackers. This analysis can help rationalize
what attacks each asset needs to be protected against.
The analysis should also include a description of who is explicitly trusted with access
to assets stored on the device. This can highlight weaknesses in the security model.
There have been a number of published cases in which consumer data has been stolen
from devices by maintenance or repair technicians, and subsequently published on the
internet.
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