CVE-2021-0115: Intel Atom C3308 Privilege Escalation Flaw

CVE-2021-0115 Overview

CVE-2021-0115 is a buffer overflow vulnerability in the firmware for multiple Intel processor families that may allow a privileged user to escalate privileges through local access. This firmware-level vulnerability affects a wide range of Intel products including Intel Core (3rd through 11th generation), Intel Xeon (Bronze, Silver, Gold, Platinum, W, D, and E series), Intel Atom C3000 series, and Intel Core M processors.

The vulnerability exists in the BIOS/UEFI firmware layer, making it particularly concerning as firmware-level attacks can persist across operating system reinstalls and evade traditional security controls. Exploitation requires local access with elevated privileges, but successful exploitation can result in complete system compromise with impacts to confidentiality, integrity, and availability.

Critical Impact

A privileged local attacker can exploit this buffer overflow in Intel processor firmware to escalate privileges, potentially gaining persistent low-level system access that survives OS reinstallation.

Affected Products

• Intel Core i3, i5, i7, i9 Processors (6th through 11th Generation)
• Intel Xeon Scalable Processors (Bronze, Silver, Gold, Platinum series)
• Intel Xeon W, D, and E Series Processors
• Intel Atom C3000 Series Processors
• Intel Core M Series Processors
• NetApp Cloud Backup
• NetApp FAS/AFF BIOS

Discovery Timeline

• February 9, 2022 - CVE-2021-0115 published to NVD
• May 5, 2025 - Last updated in NVD database

Technical Details for CVE-2021-0115

Vulnerability Analysis

This buffer overflow vulnerability (CWE-120: Buffer Copy without Checking Size of Input) resides within the firmware layer of affected Intel processors. The vulnerability allows data to be written beyond the boundaries of an allocated buffer in the processor firmware, which can corrupt adjacent memory regions and alter program execution flow.

Firmware vulnerabilities are particularly dangerous because they operate below the operating system level, in the pre-boot environment where traditional endpoint security solutions have limited visibility. An attacker who successfully exploits this vulnerability could install persistent implants that survive operating system reinstallation, disable security features, or gain complete control over the affected system.

The attack requires local access and elevated privileges, which limits the exposure surface but doesn't diminish the severity for environments where attackers may have already established an initial foothold. In enterprise environments, this could enable lateral movement with persistent access, making remediation significantly more complex.

Root Cause

The root cause is a classic buffer overflow condition (CWE-120) where the firmware code performs buffer copy operations without adequately validating the size of input data against the destination buffer's capacity. When input data exceeds the buffer size, it overwrites adjacent memory regions, potentially corrupting control structures, function pointers, or other critical data.

In the context of BIOS/UEFI firmware, such memory corruption can lead to arbitrary code execution in System Management Mode (SMM) or other privileged execution contexts that have unrestricted access to all system resources.

Attack Vector

The attack vector for CVE-2021-0115 requires local access to the target system with high privileges already obtained. An attacker would need to:

1. Gain initial access to the target system through another vulnerability or social engineering
2. Escalate privileges to administrator or root level
3. Craft malicious input that triggers the buffer overflow in the firmware
4. Execute the payload to achieve further privilege escalation at the firmware level

Successful exploitation enables persistent compromise at the firmware layer, potentially allowing the attacker to install bootkits, disable Secure Boot, or maintain access that persists across operating system reinstallation.

Detection Methods for CVE-2021-0115

Indicators of Compromise

• Unexpected BIOS/UEFI firmware modifications or version changes
• Secure Boot violations or unexplained Secure Boot disablement
• Anomalous system behavior during boot sequence
• Unexplained firmware update events in system logs

Detection Strategies

• Monitor firmware integrity using platform-specific tools such as Intel Boot Guard or CHIPSEC
• Deploy endpoint detection solutions with firmware visibility capabilities
• Implement hardware-based attestation to verify firmware integrity at boot time
• Audit system event logs for suspicious BIOS/UEFI modification attempts

Monitoring Recommendations

• Enable and monitor UEFI Secure Boot status across all affected systems
• Implement centralized firmware version tracking to identify systems running vulnerable firmware
• Configure alerts for firmware downgrade attempts or unauthorized modifications
• Utilize SentinelOne's deep visibility capabilities to detect anomalous pre-boot or firmware-level activity

How to Mitigate CVE-2021-0115

Immediate Actions Required

• Inventory all systems with affected Intel processors to determine exposure
• Prioritize firmware updates for systems in high-risk environments or with sensitive data
• Verify Secure Boot is enabled and properly configured on all affected systems
• Review and restrict local administrative access to minimize attack surface

Patch Information

Intel has released firmware updates to address this vulnerability as detailed in Intel Security Advisory SA-00527. System administrators should obtain updated BIOS/UEFI firmware from their system or motherboard manufacturer, as Intel provides microcode and firmware updates to OEM vendors for distribution.

NetApp has also released guidance for affected products in their Security Advisory NTAP-20220210-0007.

For firmware updates:

• Contact your OEM or motherboard manufacturer for the latest BIOS/UEFI update
• Follow manufacturer instructions for firmware update procedures
• Create system backups before applying firmware updates
• Verify successful update by checking the BIOS version post-installation

Workarounds

• Enable and enforce UEFI Secure Boot to help prevent unauthorized firmware modifications
• Restrict local administrative access using principle of least privilege
• Implement physical security controls to prevent unauthorized console access
• Enable BIOS/UEFI password protection to prevent unauthorized firmware changes
• Consider deploying hardware-based attestation solutions for critical systems

# Example: Check BIOS version on Linux systems
sudo dmidecode -t bios | grep -i version

# Example: Verify Secure Boot status on Linux
mokutil --sb-state

# Example: Check BIOS version on Windows (PowerShell)
Get-WmiObject -Class Win32_BIOS | Select-Object SMBIOSBIOSVersion, ReleaseDate