CWE-1256 Base Stable

Improper Restriction of Software Interfaces to Hardware Features

This vulnerability occurs when a system's software interfaces to hardware features—like power, clock, or performance management—are not properly locked down. This allows attackers to misuse these…

Definition

What is CWE-1256?

This vulnerability occurs when a system's software interfaces to hardware features—like power, clock, or performance management—are not properly locked down. This allows attackers to misuse these interfaces from software to tamper with hardware memory or registers, or to gather sensitive data by observing physical side effects, without needing physical access to the device.
Many developers assume that attacks like fault injection or side-channel analysis require an attacker to physically touch the device. This assumption breaks down when software can directly control hardware features like voltage, clock speed, or power meters. Attackers can exploit these poorly restricted interfaces from a standard application to deliberately cause bit errors (faults) or to measure power consumption patterns, leading to privilege escalation, authentication bypass, or cryptographic key extraction. Common examples include abusing dynamic voltage and frequency scaling (DVFS) to induce faults, using hardware power meters (e.g., Intel RAPL) for side-channel analysis, or triggering Rowhammer-style bit flips via rapid memory accesses. Managing this at scale is difficult; an ASPM like Plexicus can help you track and remediate these hardware-interface flaws across your entire stack, correlating code patterns with potential runtime exploitation.
Real-world impact

Real-world CVEs caused by CWE-1256

  • CVE-2019-11157

    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].

  • CVE-2020-8694

    PLATYPUS Attack: Insufficient access control in the Linux kernel driver for some Intel processors allows information disclosure.

  • CVE-2020-8695

    Observable discrepancy in the RAPL interface for some Intel processors allows information disclosure.

  • CVE-2020-12912

    AMD extension to a Linux service does not require privileged access to the RAPL interface, allowing side-channel attacks.

  • CVE-2015-0565

    NaCl in 2015 allowed the CLFLUSH instruction, making Rowhammer attacks possible.

How attackers exploit it

Step-by-step attacker path

  1. 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.

  2. 2

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

  3. 3

    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.

  4. 4

    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.

  5. 5

    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.

Vulnerable code example

Vulnerable Other

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.

Vulnerable Other 
Continuously writing the same value to the same address causes the value of an adjacent location to change value.
Secure code example

Secure Other

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

Secure Other 
Redesign the RAM devices to reduce inter capacitive coupling making the Rowhammer exploit impossible.
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-1256

  • Architecture and Design / Implementation Ensure proper access control mechanisms protect software-controllable features altering physical operating conditions such as clock frequency and voltage.
Detection signals

How to detect CWE-1256

Manual Analysis

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

Automated Dynamic Analysis Moderate

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.

Plexicus auto-fix

Plexicus auto-detects CWE-1256 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-1256?

This vulnerability occurs when a system's software interfaces to hardware features—like power, clock, or performance management—are not properly locked down. This allows attackers to misuse these interfaces from software to tamper with hardware memory or registers, or to gather sensitive data by observing physical side effects, without needing physical access to the device.

How serious is CWE-1256?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-1256?

MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, Not Technology-Specific, Memory Hardware, Power Management Hardware, Clock/Counter Hardware.

How can I prevent CWE-1256?

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

How does Plexicus detect and fix CWE-1256?

Plexicus's SAST engine matches the data-flow signature for CWE-1256 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-1256?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1256.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1256

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CWE-863 Sibling

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CWE-926 Sibling

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Resources

Further reading

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