CVE-2020-12358: Intel BIOS Denial of Service Vulnerability

CVE-2020-12358 Overview

CVE-2020-12358 is an out-of-bounds write vulnerability affecting the firmware (BIOS) for a wide range of Intel processors. This firmware-level flaw allows a privileged user with local access to potentially trigger a denial of service condition. The vulnerability impacts multiple generations of Intel Core, Xeon, and other processor families, as well as products from Siemens and NetApp that incorporate affected Intel processors.

Critical Impact

A privileged attacker with local system access can exploit this firmware vulnerability to cause system instability or denial of service, potentially disrupting critical infrastructure and enterprise environments.

Affected Products

• Intel BIOS firmware for Core i3, i5, i7, i9 processors (6th through 11th generation)
• Intel Xeon Bronze, Silver, Gold, Platinum, E3, E5, E7, D, E, and W series processors
• Siemens SIMATIC IPC547G industrial PCs
• NetApp AFF, FAS, E-Series, HCI Compute Node, HCI Storage Node, and SolidFire BIOS
• NetApp Cloud Backup

Discovery Timeline

• 2021-06-09 - CVE-2020-12358 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-12358

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption flaw that occurs when firmware code writes data beyond the boundaries of an allocated memory buffer. In the context of Intel processor firmware, this type of vulnerability can lead to corruption of adjacent memory regions, causing unpredictable system behavior or complete system failure.

The vulnerability requires local access and high privileges to exploit, which limits the attack surface but makes it particularly dangerous in scenarios involving insider threats or compromised administrator accounts. Exploitation does not require user interaction, meaning an attacker with sufficient privileges can trigger the vulnerability programmatically.

Root Cause

The root cause of CVE-2020-12358 lies in improper bounds checking within the Intel BIOS firmware code. When processing certain inputs or operations, the firmware fails to validate that write operations remain within the allocated buffer boundaries. This oversight allows data to be written to unintended memory locations, potentially overwriting critical firmware structures or control data.

The out-of-bounds write condition can occur during firmware initialization, runtime operations, or when handling specific system management mode (SMM) requests, though specific technical details have not been publicly disclosed by Intel.

Attack Vector

Exploitation of this vulnerability requires an attacker to have:

1. Local access to the target system - remote exploitation is not possible
2. High privileges - administrative or root-level access is required
3. Ability to interact with firmware - through system management interfaces or BIOS configuration utilities

The attack scenario involves a privileged user crafting specific inputs or triggering particular firmware code paths that lead to the out-of-bounds write condition. While the primary impact is denial of service (system crash or hang), such firmware-level vulnerabilities could potentially have more severe implications if chained with other vulnerabilities.

The attacker does not require any user interaction to exploit this vulnerability once they have established privileged local access to the target system.

Detection Methods for CVE-2020-12358

Indicators of Compromise

• Unexpected system reboots or crashes without clear cause on systems with affected Intel processors
• BIOS/firmware errors logged in system event logs or IPMI/BMC logs
• System management mode (SMM) exceptions or errors in hardware monitoring tools
• Unexplained firmware corruption detected during integrity checks

Detection Strategies

• Implement hardware inventory management to identify systems with affected Intel processors and outdated BIOS versions
• Monitor system stability metrics for anomalous reboot patterns that may indicate exploitation attempts
• Enable and review firmware integrity logging through platform-specific management tools (Intel Management Engine, BMC interfaces)
• Deploy endpoint detection solutions capable of monitoring privileged operations that interact with firmware interfaces

Monitoring Recommendations

• Regularly audit administrative and privileged account access to systems with affected Intel processors
• Configure alerting for multiple consecutive system crashes or unexpected reboots
• Implement BIOS/UEFI secure boot and firmware integrity verification where supported
• Monitor for unauthorized changes to BIOS settings or firmware update attempts

How to Mitigate CVE-2020-12358

Immediate Actions Required

• Identify all systems in your environment running affected Intel processors by cross-referencing hardware inventory against the Intel Security Advisory
• Prioritize patching for systems in critical infrastructure, data centers, and industrial control environments
• Restrict administrative access to affected systems to minimize the attack surface until patches can be applied
• Enable firmware write protection features where available to prevent unauthorized firmware modifications

Patch Information

Intel has released BIOS firmware updates to address this vulnerability. Organizations should obtain patches from their respective hardware vendors:

• Intel: Refer to Intel Security Advisory SA-00463 for official guidance and firmware update information
• Siemens: Industrial PC users should review Siemens Security Advisory SSA-309571 for SIMATIC IPC547G firmware updates
• NetApp: Storage and HCI customers should consult NetApp Security Advisory NTAP-20210702-0002 for applicable product updates

BIOS updates typically require system reboots and should be scheduled during maintenance windows to minimize operational impact.

Workarounds

• Implement strict access controls to limit which users have administrative privileges on affected systems
• Enable BIOS password protection to prevent unauthorized firmware configuration changes
• Where possible, enable firmware write protection (BIOS Lock) to prevent runtime firmware modifications
• Segment networks to isolate systems with affected processors from untrusted network segments
• Consider implementing additional monitoring for privileged user activities on critical systems until patches are deployed

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

# Example: Verify current BIOS version (requires root)
dmidecode -s bios-version

# List all systems requiring BIOS updates (example with dmidecode)
dmidecode -t bios | grep -E "Vendor|Version|Release"