CVE-2022-33023 in CVA6
Summary
by MITRE • 06/29/2022
CVA6 commit 909d85a gives incorrect permission to use special multiplication units when the format of instructions is wrong.
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Analysis
by VulDB Data Team • 07/16/2022
The vulnerability identified as CVE-2022-33023 affects the CVA6 RISC-V processor implementation, specifically within the instruction decoding and execution logic that governs special multiplication units. This flaw resides in the commit 909d85a of the CVA6 core, which represents a significant security concern for systems relying on this processor architecture. The vulnerability manifests when instructions are processed with incorrect formatting, creating a scenario where unauthorized access to specialized hardware multiplication units occurs.
The technical flaw stems from insufficient validation mechanisms within the instruction pipeline that should enforce proper formatting before granting access to dedicated multiplication hardware. When an instruction arrives with malformed operands or incorrect encoding, the processor fails to properly check the instruction format before allowing access to the special multiplication units. This misconfiguration creates a privilege escalation path where malicious code could potentially bypass normal access controls and directly utilize hardware multiplication resources that should only be available under specific valid instruction formats.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it could enable attackers to manipulate the processor's multiplication operations in ways that compromise system integrity and potentially lead to information disclosure or denial of service conditions. The special multiplication units in question likely handle specific arithmetic operations that are critical for cryptographic functions, signal processing, or other performance-sensitive operations where unauthorized access could result in data corruption or system instability. This vulnerability particularly affects embedded systems, IoT devices, and other applications where the CVA6 processor is deployed and where predictable behavior of arithmetic units is essential for security.
Systems utilizing the CVA6 processor architecture should implement immediate mitigations including firmware updates that correct the instruction format validation logic, enhanced runtime monitoring for anomalous multiplication unit access patterns, and comprehensive code review processes to identify similar vulnerabilities in instruction processing pipelines. Organizations should also consider implementing memory protection mechanisms that can detect and prevent unauthorized access attempts to specialized hardware units, aligning with mitigations recommended under the ATT&CK framework for privilege escalation techniques. The vulnerability aligns with CWE-284, which addresses improper access control, and represents a critical security gap that requires immediate attention to prevent potential exploitation in environments where the processor handles sensitive operations.