External risk intelligence

Windows Driver Privilege Escalation Vulnerability.

CVE advisoryKnown Exploit

CVE-2021-36955

A flaw in the Windows Common Log File System Driver can allow a user with limited access to gain elevated privileges on a system. This could lead to unauthorized access, data compromise, or service disruption, posing a business risk. Organizations should apply vendor security updates to mitigate this vulnerability.

1Halo Surface Signal

Microsoft Windows 10 1507

before 10.0.10240.19060before 10.0.14393.4651before 10.0.17763.2183before 10.0.18363.1801before 10.0.19041.1237before 10.0.19042.1237before 10.0.19043.1237r2before 10.0.20348.230

External exposure likelihood

Halo Surface Signal score for CVE-2021-36955

This vulnerability resides within a Windows kernel-mode driver, requiring local access to the system. It is a local privilege escalation issue and is not reachable via the public internet in any standard deployment.

Horizon Alert

Summary of the vulnerability and why it matters

The Windows Common Log File System Driver contains a flaw that could allow unauthorized users to gain elevated permissions. This could lead to significant business disruption and risk if exploited.

  • Vulnerable Windows component
  • Flaw allows privilege escalation
  • Potential for significant business impact

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker to gain elevated privileges on a system. The attack involves exploiting a flaw in the Windows Common Log File System driver. Successful exploitation could enable an attacker to execute arbitrary code with elevated permissions, potentially leading to further compromise of the affected organization. This could impact the confidentiality, integrity, and availability of systems and data.

  • Local system access required.
  • Attacker triggers driver vulnerability.
  • Control or impact results.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability allows an attacker with limited access to a Windows system to gain elevated privileges. Exploitation could result in unauthorized access to sensitive data, disruption of services, or further compromise of the affected system. The potential for significant business risk warrants prompt attention to mitigation efforts.

  • Likely attacker skill level: Low.
  • Required access or conditions: Local system access.
  • Business risk or urgency: High.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Windows operating system, potentially allowing for elevation of privileges on affected systems. Organizations should prioritize identifying all systems running vulnerable versions of Windows to understand their exposure. Addressing this vulnerability involves implementing the vendor's provided security updates.

  • Find affected Windows assets.
  • Isolate or reduce exposure.
  • Apply fix, verify, and monitor.

Frequently asked questions

What is the Windows Common Log File System Driver Elevation of Privilege Vulnerability (CVE-2021-36955)?

CVE-2021-36955 is a vulnerability in the Windows Common Log File System Driver that allows for local privilege escalation. An attacker with limited access to a Windows system can exploit this flaw to gain elevated privileges, potentially leading to unauthorized access to sensitive data or further system compromise.

How does the Windows Common Log File System Driver vulnerability work?

This vulnerability exists within a Windows kernel-mode driver. An attacker with local system access triggers a flaw in the Common Log File System driver, which can result in privilege escalation. This means an attacker can gain higher-level permissions than they initially possessed.

What is the potential impact of exploiting CVE-2021-36955 on a Windows system?

Exploiting this vulnerability allows an attacker to execute arbitrary code with elevated permissions. This can lead to a significant business impact, including unauthorized access to sensitive data, disruption of services, and further compromise of the affected organization's systems and data.

Why is CVE-2021-36955 considered a high-risk vulnerability?

The vulnerability allows for privilege escalation, meaning an attacker can gain administrative control over a system. While it requires local access, the ability to elevate privileges poses a significant risk to the confidentiality, integrity, and availability of systems and data.

What steps should be taken to address the Windows Common Log File System Driver vulnerability?

Organizations should identify all Windows systems that are running vulnerable versions. The primary mitigation is to apply the security updates provided by Microsoft for the affected Windows operating systems. After applying the fix, verify the implementation and monitor systems for any unusual activity.

References