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CWE-1256: Improper Restriction of Software Interfaces to Hardware Features

Weakness ID: 1256
Abstraction: Base
Structure: Simple
Presentation Filter:
+ Description
The product provides software-controllable device functionality for capabilities such as power and clock management, but it does not properly limit functionality that can lead to modification of hardware memory or register bits, or the ability to observe physical side channels.
+ Extended Description

It is frequently assumed that physical attacks such as fault injection and side-channel analysis require an attacker to have physical access to the target device. This assumption may be false if the device has improperly secured power management features, or similar features. 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 and monitor power consumption are common features in today's chipsets, but they also enable attackers to mount fault injection and side-channel attacks without having physical access to the device.

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. Manipulation of the device clock and voltage supply is a well-known technique to inject faults and is cheap to implement with physical device access. Poorly protected power management features allow these attacks to be performed from software. 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, [REF-1083]).

Side channel analysis requires gathering measurement traces of physical quantities such as power consumption. Modern processors often include power metering capabilities in the hardware itself (e.g., Intel RAPL) which if not adequately protected enable attackers to gather measurements necessary for performing side-channel attacks from software.

+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.285Improper Authorization
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Hardware Design" (CWE-1194)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1206Power, Clock, and Reset Concerns
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Architecture and DesignAn architect may initiate introduction of this weakness via exacting requirements for software accessible power/clock management requirements
ImplementationAn implementer may introduce this weakness by assuming there are no consequences to unbounded power and clock management for secure components from untrusted ones.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.


Class: Language-Independent (Undetermined Prevalence)

Operating Systems

Class: OS-Independent (Undetermined Prevalence)


Class: Architecture-Independent (Undetermined Prevalence)


Class: Technology-Independent (Undetermined Prevalence)

Memory Hardware (Undetermined Prevalence)

Power Management Hardware (Undetermined Prevalence)

Clock/Counter Hardware (Undetermined Prevalence)

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

Technical Impact: Modify Memory; Modify Application Data; Bypass Protection Mechanism

+ Demonstrative Examples

Example 1

This example considers the Rowhammer problem [REF-1083]. The Rowhammer issue was caused 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.

(bad code)
Example Language: Other 
Continuously writing the same value to the same address causes the value of an adjacent location to change value.

Preventing the loop required to defeat the Rowhammer exploit is not always possible:

(good code)
Example Language: Other 
Redesign the RAM devices to reduce inter capacitive coupling making the Rowhammer 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 2

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.

Example 3

Consider the following SoC design. Security-critical settings for scaling clock frequency and voltage are available in a range of registers bounded by [PRIV_END_ADDR : PRIV_START_ADDR] in the tmcu.csr module in the HW Root of Trust. These values are writable based on the lock_bit register in the same module. The lock_bit is only writable by privileged software running on the tmcu.

Hardware Root of Trust

We assume that untrusted software running on any of the Core{0-N} processors has access to the input and output ports of the hrot_iface. If untrusted software can clear the lock_bit or write the clock frequency and voltage registers due to inadequate protection, a fault injection attack could be performed.

+ Observed Examples
Plundervolt: Improper conditions check in voltage settings for some Intel(R) Processors may allow a privileged user to potentially enable escalation of privilege and/or information disclosure via local access [REF-1081].
PLATYPUS Attack: Insufficient access control in the Linux kernel driver for some Intel processors allows information disclosure.
Observable discrepancy in the RAPL interface for some Intel processors allows information disclosure.
AMD extension to a Linux service does not require privileged access to the RAPL interface, allowing side-channel attacks.
NaCl in 2015 allowed the CLFLUSH instruction, making Rowhammer attacks possible.
+ Potential Mitigations

Phases: Architecture and Design; Implementation

Ensure proper access control mechanisms protect software-controllable features altering physical operating conditions such as clock frequency and voltage.

+ Weakness Ordinalities
(where the weakness exists independent of other weaknesses)
+ Detection Methods

Manual Analysis

Perform a security evaluation of system-level architecture and design with software-aided physical attacks in scope.

Automated Dynamic Analysis

Use custom software to change registers that control clock settings or power settings to try to bypass security locks, or repeatedly write DRAM to try to change adjacent locations. This can be effective in extracting or changing data. The drawback is that it cannot be run before manufacturing, and it may require specialized software.

Effectiveness: Moderate

+ Functional Areas
  • Power
  • Clock
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
MemberOfViewView - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).1343Weaknesses in the 2021 CWE Most Important Hardware Weaknesses List
+ References
[REF-1081] Kit Murdock, David Oswald, Flavio D Garcia, Jo Van Bulck, Frank Piessens and Daniel Gruss. "Plundervolt". <>.
[REF-1082] Adrian Tang, Simha Sethumadhavan and Salvatore Stolfo. "CLKSCREW: Exposing the Perils of Security-Oblivious Energy Management". <>.
[REF-1083] Yoongu Kim, Ross Daly, Jeremie Kim, Ji Hye Lee, Donghyuk Lee, Chris Wilkerson, Konrad Lai and Onur Mutlu. "Flipping Bits in Memory Without Accessing Them: An Experimental Study of DRAM Disturbance Errors". <>.
[REF-1225] Project Zero. "Exploiting the DRAM rowhammer bug to gain kernel privileges". 2015-03-09. <>.
[REF-1217] Ross Anderson. "Security Engineering". 2001. <>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2020-05-08Nicole FernTortuga Logic
+ Contributions
Contribution DateContributorOrganization
2021-07-16Tortuga Logic
Provided Demonstrative Example for Hardware Root of Trust
2021-10-11Anders Nordstrom, Alric AlthoffTortuga Logic
Provided detection method
2021-10-15Nicole FernRiscure
updated description and extended description, detection method, and observed examples
+ Modifications
Modification DateModifierOrganization
2020-08-20CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Maintenance_Notes, Related_Attack_Patterns
2021-03-15CWE Content TeamMITRE
updated Demonstrative_Examples, Functional_Areas, Maintenance_Notes
2021-07-20CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples
2021-10-28CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Detection_Factors, Maintenance_Notes, Modes_of_Introduction, Name, Observed_Examples, References, Relationships, Weakness_Ordinalities
2022-04-28CWE Content TeamMITRE
updated Applicable_Platforms
2022-06-28CWE Content TeamMITRE
updated Applicable_Platforms
+ Previous Entry Names
Change DatePrevious Entry Name
2021-10-28Hardware Features Enable Physical Attacks from Software
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Page Last Updated: June 28, 2022