External risk intelligence

Windows Kernel Elevation of Privilege Vulnerability

CVE advisoryKnown Exploit

CVE-2021-33771

A Windows Kernel privilege escalation vulnerability affects affected organizations. This flaw allows local attackers to gain elevated control of systems, posing a risk of unauthorized data access and operational disruption.

1Halo Surface Signal

Microsoft Windows 10 1507

before 10.0.10240.19003before 10.0.14393.4530before 10.0.17763.2061before 10.0.18363.1679before 10.0.19041.1110before 10.0.19042.1110before 10.0.19043.1110

External exposure likelihood

Halo Surface Signal score for CVE-2021-33771

This vulnerability resides within the Windows Kernel and requires a local attacker to execute code on the system. It is not reachable via the public internet, as it is fundamentally a local privilege escalation issue requiring existing local access.

Horizon Alert

Summary of the vulnerability and why it matters

The Windows Kernel contains a privilege escalation vulnerability. This flaw allows an attacker with local access to gain higher levels of control over the affected system. The primary business risk involves unauthorized access to sensitive data and potential disruption of critical operations.

  • Windows Kernel
  • Privilege escalation flaw
  • Unauthorized data access

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker with local access to a system to gain elevated privileges. The attack exploits a flaw in the Windows kernel that can be triggered by a malicious application. Successful exploitation would allow an attacker to execute arbitrary code with system-level permissions, potentially leading to a complete compromise of the affected system. This could impact the confidentiality, integrity, and availability of data and systems.

  • Local system access required.
  • Malicious application execution.
  • Elevated control achieved.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability allows an attacker with limited access to a system to gain elevated privileges, potentially impacting the confidentiality, integrity, and availability of data and systems. Exploitation could lead to significant business risk if an attacker can achieve administrative control over affected systems. The confirmed presence of this vulnerability in exploited campaigns suggests that organizations should treat it with a high degree of urgency.

  • Low to moderate attacker skill level
  • Requires local system access
  • High business risk and urgency

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

The identified Windows Kernel Elevation of Privilege Vulnerability presents a risk to affected organizations. Attackers could potentially escalate privileges on impacted systems, leading to unauthorized access and modification of data. This could result in significant business risk and operational disruption.

  • Identify all Windows systems.
  • Isolate systems or limit access.
  • Apply vendor updates and verify.
  • Monitor for suspicious activity.

Frequently asked questions

What is the Windows Kernel Elevation of Privilege Vulnerability (CVE-2021-33771)?

CVE-2021-33771 is a vulnerability within the Windows operating system's kernel. The kernel is a core component that manages the system's resources and interacts directly with hardware. This vulnerability allows an attacker to gain higher privileges than they normally would have on an affected system, potentially leading to unauthorized access and control.

What type of weakness does CVE-2021-33771 represent?

This vulnerability is a type of privilege escalation. It allows an attacker to increase their access level on a system. Specifically, it can enable an attacker to run arbitrary code in kernel mode, which means they could install programs, modify or delete data, and create new user accounts with full administrative rights.

How can an attacker trigger this Windows kernel vulnerability?

Exploiting this vulnerability requires an attacker to first log on to the affected system. Once logged in, they can execute a specially crafted application. It's important to note that this vulnerability is not triggered by remote access; local access is a prerequisite.

Who should be concerned about the Windows Kernel Elevation of Privilege Vulnerability?

Organizations running affected versions of Microsoft Windows should be concerned. According to Halo Surface Signal, this is classified as an 'internal' vulnerability because it requires local access to a system, rather than being accessible over the internet. This means the primary risk is to systems that an attacker can physically or logically access.

What is the first step to address this Windows kernel vulnerability?

The primary and most crucial first step is to apply the security updates provided by Microsoft for the affected Windows systems. Regularly updating your operating system ensures that known vulnerabilities like this are patched and mitigated.

References