CVE-2020-0528: Intel Core Privilege Escalation Flaw

CVE-2020-0528 Overview

CVE-2020-0528 is a BIOS firmware vulnerability affecting Intel Core processors from the 7th through 10th generations. The vulnerability stems from improper buffer restrictions in the BIOS firmware, which may allow an authenticated user with local access to potentially achieve privilege escalation or cause a denial of service condition.

This firmware-level vulnerability is particularly concerning because BIOS/UEFI vulnerabilities operate below the operating system level, making them difficult to detect with traditional security tools. Exploitation requires local access and authentication, but successful attacks could grant attackers elevated privileges or disrupt system availability at the firmware layer.

Critical Impact

Authenticated local attackers can exploit improper buffer handling in BIOS firmware to escalate privileges or cause denial of service on systems with 7th-10th Gen Intel Core processors.

Affected Products

• Intel Core i5 7th Generation (Kaby Lake) Processor Family and Firmware
• Intel Core i7 7th, 8th, and 10th Generation Processor Families and Firmware
• Intel Core i9 9th Generation Processor Family and Firmware

Discovery Timeline

• June 15, 2020 - CVE-2020-0528 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-0528

Vulnerability Analysis

This vulnerability exists within the BIOS firmware implementation across multiple generations of Intel Core processors. The flaw involves improper buffer restrictions, a class of memory safety issues where the firmware fails to adequately validate or constrain buffer operations. When BIOS code processes certain data or operations without proper boundary checks, memory adjacent to the intended buffer may be corrupted or accessed.

BIOS firmware operates in System Management Mode (SMM), one of the most privileged execution environments on x86 systems. SMM code runs at a higher privilege level than the operating system kernel, making vulnerabilities in this layer extremely dangerous. An attacker who can exploit buffer handling flaws in BIOS firmware may be able to execute code in SMM context or corrupt critical firmware data structures.

The local access requirement means an attacker must have already gained some level of access to the target system. However, once local access is achieved, exploitation could allow the attacker to bypass operating system security controls, persist across reboots, or render the system unusable.

Root Cause

The root cause of CVE-2020-0528 is improper buffer restrictions within the BIOS firmware code. This typically manifests when firmware routines that handle data buffers fail to properly validate buffer sizes, boundaries, or indices before performing read or write operations. Without these checks, operations may overflow the intended buffer, corrupting adjacent memory regions or allowing controlled writes to unintended locations.

In the context of BIOS firmware, such buffer handling issues often occur in code paths that process configuration data, hardware initialization parameters, or SMM handler routines. The firmware's privileged execution context means that memory corruption can have severe consequences, potentially affecting system stability or security boundaries.

Attack Vector

The attack vector for CVE-2020-0528 requires local access to the affected system with authenticated user privileges. The exploitation scenario involves:

1. An attacker with local user access identifies a vulnerable system running affected Intel Core processor firmware
2. The attacker crafts input or triggers operations that interact with the vulnerable BIOS buffer handling routines
3. The improper buffer restrictions allow the attacker to corrupt memory or manipulate firmware behavior
4. Successful exploitation results in privilege escalation within the firmware context or denial of service

The local access requirement limits the attack surface compared to remotely exploitable vulnerabilities. However, in enterprise environments with shared workstations, kiosks, or systems accessible to multiple users, this vulnerability presents a significant risk. Additionally, attackers who have achieved initial compromise through other means could leverage this vulnerability for persistence or privilege escalation.

Detection Methods for CVE-2020-0528

Indicators of Compromise

• Unexpected system crashes or blue screens during boot or resume operations that may indicate firmware corruption
• Anomalous SMM-related events or unexpected System Management Interrupt (SMI) activity logged by firmware security tools
• Unauthorized BIOS configuration changes or firmware modifications detected during integrity checks

Detection Strategies

• Deploy firmware integrity monitoring solutions that can detect unauthorized modifications to BIOS/UEFI code and configurations
• Implement hardware asset inventory tracking to identify systems running affected Intel Core processor generations
• Enable Secure Boot and audit boot process logs for indications of tampering or unexpected firmware behavior
• Utilize endpoint detection solutions capable of monitoring for exploitation attempts targeting firmware vulnerabilities

Monitoring Recommendations

• Maintain comprehensive hardware and firmware inventory to track systems requiring BIOS updates
• Monitor for Intel security advisory updates and OEM firmware release notifications
• Implement privileged access monitoring to detect suspicious local access patterns that may precede exploitation attempts

How to Mitigate CVE-2020-0528

Immediate Actions Required

• Identify all systems in your environment containing affected Intel Core processors from the 7th through 10th generations
• Contact your system OEM (Dell, HP, Lenovo, etc.) to obtain updated BIOS firmware that addresses this vulnerability
• Apply BIOS updates using OEM-recommended procedures during scheduled maintenance windows
• Restrict local administrative access to systems to reduce the pool of potential attackers

Patch Information

Intel has addressed this vulnerability through BIOS firmware updates distributed via OEM partners. System administrators should consult the Intel Security Advisory SA-00322 for specific details about the vulnerability and remediation guidance.

Since BIOS updates are typically delivered through system manufacturers rather than directly from Intel, organizations should check with their specific hardware vendors (Dell, HP, Lenovo, ASUS, etc.) for updated firmware releases. The update process varies by manufacturer and may require:

• Downloading firmware updates from the OEM support portal
• Using OEM-provided update utilities
• Following vendor-specific installation procedures
• Scheduling system downtime for firmware installation and reboot

Workarounds

• Restrict physical and local access to affected systems to trusted administrators only
• Implement application allowlisting to prevent unauthorized executables that might attempt firmware exploitation
• Enable Secure Boot and configure firmware passwords to prevent unauthorized BIOS configuration changes
• Monitor affected systems for suspicious activity until firmware updates can be applied

# Example: Check Intel processor generation on Linux systems
cat /proc/cpuinfo | grep -E "model name|cpu family"

# Example: Query BIOS version information
sudo dmidecode -t bios | grep -E "Vendor|Version|Release"