External risk intelligence

Microsoft Windows Driver Privilege Escalation Vulnerability

CVE advisoryKnown Exploit

CVE-2021-43226

This vulnerability resides within a local Windows operating system driver. It requires local access to the system to exploit and is not reachable via the public internet, consistent with local-only components.

Microsoft Windows 10 1507

before 10.0.10240.19145before 10.0.14393.4825before 10.0.17763.2366before 10.0.18363.1977before 10.0.19041.1415before 10.0.19042.1415before 10.0.19043.1415before 10.0.19044.1415befo...

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists within the Windows Common Log File System Driver. This flaw allows an attacker with local access to escalate their privileges on a targeted system. The impact can include unauthorized access to sensitive data or the execution of malicious code.

Windows Common Log File System Driver
Privilege escalation
Unauthorized data access

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker with local access to elevate their privileges on a Windows system. The attack targets the Windows Common Log File System Driver, enabling an attacker to gain higher levels of control than initially permitted. This could impact system integrity and data confidentiality by allowing unauthorized actions.

Local access required for exposure.
Attacker triggers driver vulnerability.
Results in elevated system control.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability in the Windows Common Log File System Driver could permit an attacker with existing local access to elevate their privileges. This means an attacker could gain higher levels of control over a compromised system. The potential impact includes unauthorized access to sensitive data, disruption of services, or further exploitation within the network. Organizations should assess the applicability of this vulnerability to their environment and apply vendor-provided mitigations.

Low attacker skill level
Local access required
High business risk

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Windows Common Log File System Driver, potentially allowing a local attacker with privileges to escalate their access. This could enable unauthorized actions within affected systems. Organizations should prioritize identifying all systems running vulnerable versions of Windows. Understanding the scope of affected assets is the first step in managing the associated business risk.

Find affected Windows assets.
Reduce exposure or isolate risk.
Fix, verify, and monitor.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Windows Common Log File System Driver and its role in system security?

The Windows Common Log File System Driver is a core component of the Windows operating system. It functions as a system for managing log files, which record various events and operational data. This driver is essential for troubleshooting issues and for security monitoring by recording system activities.

What type of vulnerability is CVE-2021-43226 and what does privilege escalation mean?

CVE-2021-43226 is classified as a privilege escalation vulnerability. This means that a user or attacker who already has some level of access to a system can exploit this weakness to obtain a higher level of permissions or control than they were originally granted, potentially leading to unauthorized actions.

How does an attacker exploit the Windows Common Log File System Driver vulnerability?

An attacker with existing local access to a Windows system can trigger this vulnerability within the Common Log File System Driver. Successful exploitation allows the attacker to elevate their privileges, gaining greater control over the system than their initial access level would normally permit.

What is the significance of CVE-2021-43226, especially concerning the Halo Surface Signal?

CVE-2021-43226 is a privilege escalation vulnerability in Windows. The Halo Surface Signal indicates this vulnerability is considered 'Very unlikely' to be exploited remotely because it requires local access to the system, a characteristic typical of local-only driver vulnerabilities.

What are the recommended steps for addressing the Windows Common Log File System Driver vulnerability?

To address this vulnerability, organizations should first identify all Windows assets that may be running vulnerable versions. Understanding the scope of affected systems is crucial for risk management. After identification, the next steps involve isolating affected systems if necessary, applying vendor-provided mitigations or fixes, verifying the remediation, and implementing ongoing monitoring.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.