External risk intelligence

Windows Kernel Privilege Escalation Vulnerability.

CVE advisoryKnown Exploit

CVE-2021-31979

This vulnerability is located within the Windows Kernel and requires local access to the system to exploit. It does not provide a network-accessible service or interface, and it is not reachable via the public internet in standard deployment patterns.

Memory Corruption

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 10.0.19043.1110r2

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 in the Windows Kernel could allow an attacker to gain elevated privileges on an affected system. This flaw could enable unauthorized access to sensitive data or system functions. The potential impact includes unauthorized modifications to system settings or the execution of malicious code.

Vulnerable component: Windows Kernel
Core weakness: Unspecified flaw allowing privilege escalation
Main business impact: Unauthorized system access and control

Attack Path

How an attacker could exploit the issue

This vulnerability allows an attacker with local access to elevate their privileges on a vulnerable Windows system. The attack exploits a flaw within the Windows kernel. Successfully exploiting this vulnerability could grant an attacker administrative-level control over the affected system.

Local access required for exposure.
Attacker triggers a flaw in the kernel.
Attacker gains elevated control.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability exists within the Windows kernel that could allow an attacker with local access to escalate their privileges. Exploiting this could lead to unauthorized access and modification of system data. The risk level is considered high due to the potential for significant data compromise.

Low attacker skill level.
Local access is required.
High business risk.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Windows Kernel could allow an attacker with local access to elevate their privileges on a system. Organizations should prioritize understanding which systems are affected and implementing the necessary security updates to mitigate the risk of exploitation.

Identify all Windows systems.
Apply vendor security updates.
Monitor systems for anomalies.

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 Kernel and what is it used for?

The Windows Kernel is the core component of the Windows operating system. It manages the system's resources, such as the CPU and memory, and provides essential services for all other software running on the computer. Essentially, it's the central control center that allows your applications to interact with your hardware.

How does CVE-2021-31979 exploit a weakness in the Windows Kernel?

CVE-2021-31979 is a privilege escalation vulnerability. This means it exploits a weakness (classified as CWE-119, a buffer overflow) within the Windows Kernel that an attacker can use to gain higher-level permissions than they are normally allowed on a system.

What are the preconditions for an attacker to exploit this vulnerability?

To exploit this vulnerability, an attacker must first have local access to the affected Windows system. The vulnerability is not triggered by network activity or remote access, meaning the attacker needs to be able to run code or commands directly on the machine.

Who should be concerned about this internal Windows Kernel vulnerability?

Organizations with internal Windows systems should be concerned. Since this vulnerability requires local access and doesn't involve internet-facing services, it poses a risk to systems within your network that an attacker could physically access or compromise through other means.

What is the first step to respond to this CVE threat?

The primary response is to identify all Windows systems within your organization that could be affected. After identification, the crucial next step is to apply the security updates provided by Microsoft to patch the vulnerability and mitigate the risk of exploitation.

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.