CyberSecBulletin
CVE-2022-21882Exploited in the wildNVD status: Analyzed

Microsoft Win32k Privilege Escalation

Published Updated By the CyberSecBulletin desk

CVE-2022-21882 is a high-severity out-of-bounds write vulnerability in Windows 10 Version 1809 from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 10.0.17763.2452 as the first without the flaw, so updating Windows 10 Version 1809 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on February 4, 2022, which means attacks have been observed in the wild, including in ransomware campaigns.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Windows 10 Version 1809 to 10.0.17763.2452 or a later version.
  2. Update Windows Server 2019 to 10.0.17763.2452 or a later version.
  3. Update Windows Server 2019 (Server Core installation) to 10.0.17763.2452 or a later version.
  4. CISA's required action: Apply updates per vendor instructions.
  5. Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
MicrosoftWindows 10 Version 180910.0.17763.0 up to, but not including, 10.0.17763.2452; 10.0.0 up to, but not including, 10.0.17763.245210.0.17763.2452
MicrosoftWindows Server 201910.0.17763.0 up to, but not including, 10.0.17763.245210.0.17763.2452
MicrosoftWindows Server 2019 (Server Core installation)10.0.17763.0 up to, but not including, 10.0.17763.245210.0.17763.2452
MicrosoftWindows 10 Version 190910.0.0 up to, but not including, 10.0.18363.203710.0.18363.2037
MicrosoftWindows 10 Version 21H110.0.0 up to, but not including, 10.0.19043.146610.0.19043.1466
MicrosoftWindows Server 202210.0.20348.0 up to, but not including, 10.0.20348.46910.0.20348.469
MicrosoftWindows 10 Version 20H210.0.0 up to, but not including, 10.0.19042.146610.0.19042.1466
MicrosoftWindows Server version 20H210.0.0 up to, but not including, 10.0.19042.146610.0.19042.1466
MicrosoftWindows 11 version 21H210.0.0 up to, but not including, 10.0.22000.43410.0.22000.434
MicrosoftWindows 10 Version 21H210.0.19043.0 up to, but not including, 10.0.19044.146610.0.19044.1466
MicrosoftWindows 10 1809before 10.0.17763.245210.0.17763.2452
MicrosoftWindows 10 1909before 10.0.18363.203710.0.18363.2037
MicrosoftWindows 10 20h2before 10.0.19042.146610.0.19042.1466
MicrosoftWindows 10 21h1before 10.0.19043.146610.0.19043.1466
MicrosoftWindows 10 21h2before 10.0.19044.146610.0.19044.1466
MicrosoftWindows 11 21h2before 10.0.22000.43410.0.22000.434
MicrosoftWindows Server 20h2before 10.0.19042.146610.0.19042.1466

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.0HighCNA (microsoft.com)
CVSS 3.17.8HighNVD
CVSS 2.07.2HighNVD

Official description

Win32k Elevation of Privilege Vulnerability

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  2. CVE record published.
  3. Added to CISA's Known Exploited Vulnerabilities catalogue.
  4. Deadline for US federal agencies to remediate, set by CISA.
  5. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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