CVE-2020-12357: Intel BIOS Privilege Escalation Flaw

CVE-2020-12357 Overview

CVE-2020-12357 is a BIOS/UEFI vulnerability affecting firmware for numerous Intel processors. The vulnerability stems from improper initialization in the processor firmware, which may allow a privileged user to potentially enable escalation of privilege via local access. This firmware-level flaw impacts a wide range of Intel Core, Xeon, and other processor families across multiple generations, as well as downstream products from NetApp and Siemens that incorporate affected Intel processors.

Critical Impact

A privileged attacker with local access can exploit improper firmware initialization to escalate privileges, potentially gaining deeper system control and persistence below the operating system level.

Affected Products

• Intel BIOS and firmware for Core i3, i5, i7, i9 processors (6th through 11th generation)
• Intel Xeon Scalable processors (Bronze, Silver, Gold, Platinum families)
• Intel Xeon E, E3, E5, E7, D, and W series processors
• NetApp AFF, FAS, E-Series, HCI, and SolidFire BIOS
• Siemens SIMATIC Field PG M6, IPC427E, IPC477E, IPC547G, IPC627E, IPC647E, IPC677E, IPC847E, ITP1000, and CPU 1518-4

Discovery Timeline

• June 9, 2021 - CVE-2020-12357 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-12357

Vulnerability Analysis

This vulnerability exists within the firmware initialization routines of affected Intel processors. During the boot process, certain firmware components fail to properly initialize critical data structures or security-relevant state variables. This improper initialization creates a window of opportunity where a privileged user with local system access can manipulate firmware state to achieve privilege escalation.

The firmware-level nature of this vulnerability makes it particularly concerning, as successful exploitation could allow an attacker to establish persistent access below the operating system, potentially surviving OS reinstallation and evading traditional security controls. The attack requires high privileges and local access, which somewhat limits the attack surface but represents a significant risk in scenarios involving compromised administrator accounts or insider threats.

Root Cause

The root cause is classified as CWE-665: Improper Initialization. The firmware code fails to properly initialize one or more variables, data structures, or security-relevant state during the boot or initialization sequence. When these uninitialized or improperly initialized values are subsequently used in security decisions or privilege checks, they can be exploited to bypass intended access controls.

Attack Vector

Exploitation requires local access to the affected system and elevated privileges. An attacker who has already achieved administrative or privileged access to the operating system can leverage this firmware vulnerability to escalate privileges at the firmware level. The attack vector involves:

1. Gaining privileged local access to a system with affected Intel processor firmware
2. Interacting with firmware interfaces or triggering specific boot/initialization sequences
3. Exploiting the improper initialization to manipulate firmware state
4. Achieving elevated privileges that persist at the firmware level

The vulnerability affects firmware-level execution, meaning successful exploitation could result in persistent compromise that operates below the visibility of operating system security controls. Due to the complexity of firmware exploitation and the requirement for existing privileged access, this vulnerability is more likely to be leveraged in targeted attacks or advanced persistent threat (APT) scenarios.

Detection Methods for CVE-2020-12357

Indicators of Compromise

• Unexpected BIOS/UEFI firmware modifications or version changes without authorized updates
• Anomalous system behavior during boot sequences or firmware initialization phases
• Evidence of privilege escalation attempts from already-privileged accounts targeting firmware interfaces
• Unauthorized access to firmware update utilities or BIOS configuration tools

Detection Strategies

• Monitor firmware integrity using hardware-based attestation mechanisms such as Intel TXT or TPM measurements
• Implement BIOS/UEFI monitoring solutions that track firmware version and configuration changes
• Enable Secure Boot and monitor for any attempts to bypass or disable secure boot protections
• Deploy endpoint detection solutions capable of monitoring low-level system interactions and privilege escalation attempts

Monitoring Recommendations

• Establish baseline firmware versions for all systems and alert on unauthorized changes
• Configure system event logging to capture BIOS update attempts and boot-time anomalies
• Implement privileged access monitoring to detect suspicious administrator activities targeting firmware
• Integrate firmware security monitoring with your SIEM for correlation with other security events

How to Mitigate CVE-2020-12357

Immediate Actions Required

• Review the Intel Security Advisory SA-00463 for specific firmware update guidance
• Identify all affected Intel processors in your environment using hardware inventory tools
• Apply firmware updates from system OEMs (Dell, HP, Lenovo, etc.) that incorporate Intel's fixes
• For Siemens products, consult the Siemens Security Advisory SSA-309571
• For NetApp products, review the NetApp Security Advisory NTAP-20210702-0002

Patch Information

Intel has released updated firmware to address this vulnerability. System administrators should obtain BIOS/UEFI updates from their system or motherboard manufacturers (OEMs) rather than directly from Intel, as OEMs integrate Intel firmware into their specific BIOS implementations. Contact your hardware vendor for the appropriate firmware update that addresses CVE-2020-12357.

For NetApp systems, updated BIOS firmware is available through NetApp support channels. For Siemens industrial systems, firmware updates are provided through the Siemens ProductCERT security advisory process.

Workarounds

• Restrict local administrative access to affected systems to minimize the attack surface
• Implement strong privileged access management (PAM) controls to prevent unauthorized administrator access
• Enable BIOS/UEFI password protection to restrict unauthorized firmware configuration changes
• Where possible, enable Secure Boot and other hardware security features to increase exploitation difficulty

# Example: Check current BIOS version on Linux systems
sudo dmidecode -s bios-version

# Example: Verify TPM status for firmware attestation
tpm2_getcap properties-fixed | grep -i version

# Example: Check Secure Boot status
mokutil --sb-state