CVE-2023-20528 in AMD
Summary
by MITRE • 01/11/2023
Insufficient input validation in the SMU may allow a physical attacker to exfiltrate SMU memory contents over the I2C bus potentially leading to a loss of confidentiality.
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Analysis
by VulDB Data Team • 04/07/2025
The vulnerability identified as CVE-2023-20528 represents a critical security flaw within the System Management Unit of certain processor architectures, specifically targeting the insufficient input validation mechanisms that govern communication over the I2C bus. This weakness creates an avenue for physical attackers to exploit the system's management interface and extract sensitive memory contents from the SMU, fundamentally compromising the confidentiality of system-level data. The vulnerability arises from inadequate validation of input parameters received through the I2C communication channel, which is typically used for system management and configuration purposes.
The technical implementation of this flaw stems from the SMU's failure to properly validate and sanitize data received through I2C interfaces, allowing malicious actors with physical access to manipulate or inject data that can trigger unintended memory read operations. This vulnerability falls under the broader category of insufficient input validation issues, which are commonly classified as CWE-20 - Improper Input Validation, and specifically aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: Python, when considering the potential attack vectors involving system-level communication protocols. The I2C bus, designed for low-speed communication between integrated circuits, becomes a potential attack surface when proper input validation mechanisms are absent, as the bus protocol itself does not inherently provide authentication or integrity checking.
From an operational impact perspective, this vulnerability presents a significant risk to systems where physical security is compromised or where attackers have access to the hardware level. The potential for memory contents exfiltration includes sensitive data such as cryptographic keys, system configuration parameters, and potentially other confidential information stored within the SMU's memory space. Attackers could leverage this vulnerability to gain deeper insights into system architecture and potentially escalate their attack to higher privileges or access other system components. The physical nature of the attack vector means that traditional network-based security measures would not prevent exploitation, making this a particularly concerning weakness in environments where physical access controls are insufficient or compromised.
Mitigation strategies for CVE-2023-20528 should focus on strengthening the input validation mechanisms within the SMU firmware and implementing robust I2C communication security measures. System administrators should ensure that firmware updates are applied promptly when available from vendors, as these updates typically contain fixes for such validation weaknesses. Additional protective measures include implementing physical security controls to prevent unauthorized access to system hardware, monitoring I2C bus communications for anomalous patterns, and potentially isolating critical system management functions from external I2C interfaces where possible. Organizations should also consider implementing hardware-based security features such as secure elements or trusted platform modules that can provide additional protection against such low-level memory access attacks. The vulnerability underscores the importance of designing security into hardware components from the ground up, as outlined in the security by design principles of the NIST Cybersecurity Framework, and demonstrates how weaknesses at the system management level can have cascading effects on overall system confidentiality and integrity.