Hardware Features Enable Physical Attacks from Software

Software-controllable device functionality such as power and clock management permits unauthorized modification of memory or register bits.


Fault injection attacks involve strategic manipulation of bits in a device to achieve a desired effect such as skipping an authentication step, elevating privileges, or altering the output of a cryptographic operation. Techniques employed to flip bits include low-cost methods such as manipulation of the device clock and voltage supply as well as high-cost but more precise techniques involving lasers. To inject faults a physical access requirement is frequently assumed to be necessary. This assumption may be false if the device has improperly secured power management features that allow untrusted programs to manipulate the device clock frequency or operating voltage. For mobile devices, minimizing power consumption is critical, but these devices run a wide variety of applications with different performance requirements. Software-controllable mechanisms to dynamically scale device voltage and frequency are common features in today’s chipsets and can be exploited by attackers if protections are not in place. Other features, such as the ability to write repeatedly to DRAM at a rapid rate from unprivileged software can result in bit flips in other memory locations (Rowhammer).


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

This example considers the Row-Hammar problem. .The Row-Hammar issue was caulse by a program in a tight loop writing repeatedly to a location to which the program was allowed to write but causing an adjacent memory location value to change.

Continuously writting the same value to the same address causes the value of an adjacent location to change value.

Preventing the loop required to defeat the Row-Hammar exploit is not always possible:

Redesign the RAM devices to reduce inter capacitive coupling making the Row-Hammar exploit impossible.

While the redesign may be possible for new devices, a redesign is not possible in existing devices. There is also the possibility that reducing capacitance with a relayout would impact the density of the device resulting in a less capable, more costly device.

Example Two

Suppose a hardware design implements a set of software-accessible registers for scaling clock frequency and voltage but does not control access to these registers. Attackers may cause register and memory changes and race conditions by changing the clock or voltage of the device under their control.

See Also

Power, Clock, and Reset Concerns

Weaknesses in this category are related to system power, voltage, current, temperature, clocks, system state saving/restoring, and resets at the platform and SoC level.

Comprehensive CWE Dictionary

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Weaknesses without Software Fault Patterns

CWE identifiers in this view are weaknesses that do not have associated Software Fault Patterns (SFPs), as covered by the CWE-888 view. As such, they represent gaps in...

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