The device is missing or incorrectly implements circuitry or sensors that detect and mitigate the skipping of security-critical CPU instructions when they occur.
View on MITREThe operating conditions of hardware may change in ways that cause unexpected behavior to occur, including the skipping of security-critical CPU instructions. Generally, this can occur due to electrical disturbances or when the device operates outside of its expected conditions. In practice, application code may contain conditional branches that are security-sensitive (e.g., accepting or rejecting a user-provided password). These conditional branches are typically implemented by a single conditional branch instruction in the program binary which, if skipped, may lead to effectively flipping the branch condition - i.e., causing the wrong security-sensitive branch to be taken. This affects processes such as firmware authentication, password verification, and other security-sensitive decision points. Attackers can use fault injection techniques to alter the operating conditions of hardware so that security-critical instructions are skipped more frequently or more reliably than they would in a "natural" setting.
Depending on the context, instruction skipping can have a broad range of consequences related to the generic bypassing of security critical code.
Design strategies for ensuring safe failure if inputs, such as Vcc, are modified out of acceptable ranges.
Design strategies for ensuring safe behavior if instructions attempt to be skipped.
Identify mission critical secrets that should be wiped if faulting is detected, and design a mechanism to do the deletion.
Add redundancy by performing an operation multiple times, either in space or time, and perform majority voting. Additionally, make conditional instruction timing unpredictable.
Use redundant operations or canaries to detect and respond to faults.
Ensure that fault mitigations are strong enough in practice. For example, a low power detection mechanism that takes 50 clock cycles to trigger at lower voltages may be an insufficient security mechanism if the instruction counter has already progressed with no other CPU activity occurring.
This weakness can be found using automated static analysis once a developer has indicated which code paths are critical to protect.
This weakness can be found using automated dynamic analysis. Both emulation of a CPU with instruction skips, as well as RTL simulation of a CPU IP, can indicate parts of the code that are sensitive to faults due to instruction skips.
This weakness can be found using manual (static) analysis. The analyst has security objectives that are matched against the high-level code. This method is less precise than emulation, especially if the analysis is done at the higher level language rather than at assembly level.
A smart card contains authentication credentials that are used as authorization to enter a building. The credentials are only accessible when a correct PIN is presented to the card.
There are several ways this weakness could be fixed.
A smart card contains authentication credentials that are used as authorization to enter a building. The credentials are only accessible when a correct PIN is presented to the card.
There are several ways this weakness could be fixed.
fault injection attack bypasses the verification mode, potentially allowing arbitrary code execution.
View DetailsNo relationship information available for this CWE.
CWE-1332: Improper Handling of Faults that Lead to Instruction Skips is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The device is missing or incorrectly implements circuitry or sensors that detect and mitigate the skipping of security-critical CPU instructions when they occur. The operating conditions of hardware may change in ways that cause unexpected behavior to occur, including the skipping of security-critical CPU instructions. Generally, this can occur due to electrical disturbances or when the device operates outside of its expected conditions. In practice, application code may contain conditional branches that are security-sensitive (e.g., accepting or rejecting a user-provided password). These conditional branches are typically implemented by a single conditional branch instruction in the program binary which, if skipped, may lead to effectively flipping the branch condition - i.e., causing the wrong security-sensitive branch to be taken. This affects processes such as firmware authentication, password verification, and other security-sensitive decision points. Attackers can use fault injection techniques to alter the operating conditions of hardware so that security-critical instructions are skipped more frequently or more reliably than they would in a "natural" setting.
If exploited, CWE-1332 (Improper Handling of Faults that Lead to Instruction Skips) it can compromise Confidentiality, Integrity and Authentication, leading to outcomes such as Bypass Protection Mechanism, Alter Execution Logic and Unexpected State.
Recommended mitigations for CWE-1332 include: Design strategies for ensuring safe failure if inputs, such as Vcc, are modified out of acceptable ranges. Design strategies for ensuring safe behavior if instructions attempt to be skipped. Identify mission critical secrets that should be wiped if faulting is detected, and design a mechanism to do the deletion.
CWE-1332 can be detected using Automated Static Analysis, Simulation / Emulation and Manual Analysis. Combining automated tooling with manual review typically yields the best coverage.
CWE-1332 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
MITRE documents real CVEs mapped to CWE-1332, including CVE-2019-15894. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-1332 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.