CVE-2021-33061: Intel 82599en Firmware DoS Vulnerability

CVE-2021-33061 Overview

CVE-2021-33061 is a firmware vulnerability affecting Intel 82599 Ethernet Controllers and Adapters. The vulnerability stems from insufficient control flow management within the firmware, which may allow an authenticated user with local access to cause a denial of service condition. This flaw impacts enterprise network infrastructure components commonly deployed in data centers and server environments.

Critical Impact

An authenticated local attacker can exploit insufficient control flow management in Intel 82599 Ethernet Controllers to cause denial of service, potentially disrupting network connectivity for critical systems.

Affected Products

• Intel 82599EN Ethernet Controller and Firmware
• Intel 82599EB Ethernet Controller and Firmware
• Intel 82599ES Ethernet Controller and Firmware

Discovery Timeline

• February 9, 2022 - CVE-2021-33061 published to NVD
• May 5, 2025 - Last updated in NVD database

Technical Details for CVE-2021-33061

Vulnerability Analysis

This vulnerability is classified as insufficient control flow management within the Intel 82599 series Ethernet controller firmware. The flaw exists in the firmware's handling of certain operations, where inadequate validation or enforcement of execution paths can be exploited by an authenticated local user. The attack requires local access to the system, meaning an attacker must have some level of authenticated access to the host machine where the vulnerable Ethernet controller is installed.

The impact is limited to availability, with no effect on confidentiality or integrity of data. When exploited, the vulnerability causes the network adapter to enter a non-functional state, resulting in loss of network connectivity until the system or adapter is reset.

Root Cause

The root cause lies in insufficient control flow management within the Intel 82599 Ethernet Controller firmware. Control flow management flaws occur when software or firmware fails to properly validate, restrict, or enforce the expected sequence of operations during execution. In this case, the firmware does not adequately manage certain control paths, allowing an authenticated user to trigger unexpected behavior that leads to a denial of service condition.

Attack Vector

The attack vector for CVE-2021-33061 is local, requiring an authenticated user to have direct access to the system hosting the vulnerable Intel 82599 Ethernet Controller. The attacker would need to execute malicious operations locally that interact with the Ethernet controller firmware in a way that exploits the insufficient control flow management.

The vulnerability does not require user interaction beyond the initial authenticated access. An attacker with low privileges on the local system can potentially trigger the denial of service condition by sending crafted inputs or commands that cause the firmware to enter an unexpected state.

The exploitation mechanism involves manipulating the firmware's control flow through local access, causing the Ethernet adapter to become unresponsive. For specific technical details, refer to the Intel Security Advisory SA-00571.

Detection Methods for CVE-2021-33061

Indicators of Compromise

• Unexpected loss of network connectivity on systems using Intel 82599 Ethernet Controllers
• Network adapter entering unresponsive or error state without clear network infrastructure cause
• System logs showing hardware errors or driver failures related to Intel 82599 devices

Detection Strategies

• Monitor system logs for Intel 82599 Ethernet Controller firmware errors or unexpected resets
• Implement hardware health monitoring to detect adapter failures or degraded states
• Use endpoint detection tools to identify unusual local access patterns targeting network hardware

Monitoring Recommendations

• Enable detailed logging for network adapter events and hardware status
• Implement alerting for network connectivity loss on critical servers with Intel 82599 controllers
• Monitor for repeated adapter resets or failures that may indicate exploitation attempts

How to Mitigate CVE-2021-33061

Immediate Actions Required

• Review the Intel Security Advisory SA-00571 for detailed patch and update information
• Inventory all systems with Intel 82599EN, 82599EB, or 82599ES Ethernet Controllers
• Apply firmware updates as provided by Intel through appropriate update mechanisms
• Restrict local access to systems with vulnerable Ethernet controllers to authorized users only

Patch Information

Intel has released a security advisory addressing this vulnerability. Organizations should obtain firmware updates through the Intel Security Advisory SA-00571. Additionally, NetApp customers should review the NetApp Security Advisory NTAP-20220210-0010 for product-specific guidance on affected NetApp systems using Intel 82599 controllers.

Workarounds

• Limit local access to affected systems to only trusted and necessary personnel
• Implement strong access controls and monitoring on systems with Intel 82599 controllers
• Consider network segmentation to minimize impact if denial of service occurs
• Monitor affected systems closely until firmware updates can be applied

# Check for Intel 82599 Ethernet Controllers on Linux systems
lspci | grep -i "82599"

# Verify current firmware version
ethtool -i eth0 | grep -i firmware