External risk intelligence

Microsoft Windows NTFS Elevation of Privilege Vulnerability

CVE advisoryKnown Exploit

CVE-2021-31956

A vulnerability in the Windows NTFS component allows local attackers to escalate privileges. This could impact organizations by enabling unauthorized system control and data compromise. The business risk involves potential unauthorized access to sensitive information and disruption of operations.

1Halo Surface Signal

Microsoft Windows 10 1507

before 10.0.10240.18967before 10.0.14393.4467before 10.0.17763.1999before 10.0.18363.1621before 10.0.19041.1052before 10.0.19042.1052before 10.0.19043.1052r2sp2

External exposure likelihood

Halo Surface Signal score for CVE-2021-31956

This is a local privilege escalation vulnerability within the Windows NTFS file system component. Exploitation requires an attacker to already have local access to the system to execute code. It is not reachable via the public internet or remote network vectors.

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists within the Windows NTFS component of the operating system. This flaw allows for an elevation of privilege when exploited. The potential impact includes unauthorized access and control over affected systems.

  • Vulnerable component: Windows NTFS
  • Core weakness: Elevation of privilege
  • Main business impact: Unauthorized system control

Attack Path

How an attacker could exploit the issue

This vulnerability impacts the Windows NTFS file system, allowing an attacker with local access to gain elevated privileges on a targeted system. The attack involves a specially crafted application that exploits a weakness in how NTFS handles certain operations. Successful exploitation could grant an attacker the ability to execute code with higher permissions, potentially leading to broader system compromise.

  • Local code execution required.
  • Specially crafted application triggers.
  • Attacker gains elevated privileges.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker with existing local access to a system to elevate their privileges. This means they could gain administrative control, potentially leading to unauthorized access, modification, or deletion of sensitive data, and disruption of business operations. The potential for significant damage makes this a serious concern for affected organizations.

  • 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

A vulnerability within the Windows NTFS component could allow an attacker with local access to escalate privileges. This could impact system integrity and data confidentiality by allowing unauthorized access to higher privilege levels. The organization should take immediate steps to identify and mitigate this risk.

  • Find affected systems.
  • Reduce exposure or isolate risk.
  • Fix, verify, and monitor.

Frequently asked questions

What is the Windows NTFS Elevation of Privilege Vulnerability (CVE-2021-31956)?

CVE-2021-31956 is a vulnerability in the Windows NTFS component that allows for elevation of privilege. This means an attacker with local access could gain higher permissions on the system. The core weakness is an elevation of privilege, potentially leading to unauthorized system control.

What weakness class does CVE-2021-31956 fall under?

This vulnerability is categorized under CWE-191, which relates to Integer Underflow (Issue). In the context of CVE-2021-31956, this weakness allows for an elevation of privilege within the Windows NTFS file system.

How can CVE-2021-31956 be exploited, and what is the scope of impact?

Exploitation requires an attacker to have local access to the system and execute a specially crafted application. This application triggers a weakness in how NTFS handles certain operations, granting the attacker elevated privileges. The scope is limited to systems with local access, as it is not reachable remotely.

What is the relevance of the Halo Surface Signal for CVE-2021-31956?

The Halo Surface Signal rates this vulnerability as 'Very unlikely' to be exploited remotely because it is a local privilege escalation flaw within the Windows NTFS file system. Exploitation necessitates an attacker already having local access to the system, making it not reachable via the public internet or remote network vectors.

What are the practical steps to address CVE-2021-31956?

Organizations should identify all affected systems, isolate any at-risk assets if possible, and then apply the necessary updates provided by Microsoft. Verification of the fix and continuous monitoring are crucial post-remediation to ensure system integrity and data confidentiality.

References