SB2021071356 - Multiple vulnerabilities in Microsoft Win32k

Description

This security bulletin contains information about 3 secuirty vulnerabilities.

1) Untrusted Pointer Dereference (CVE-ID: CVE-2021-34516)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to untrusted pointer dereference in DrvTransparentBltInternal() within the Microsoft Windows Canonical Display Driver cdd.dll. A local user can run a specially crafted program to execute arbitrary code with SYSTEM privileges.

2) Information disclosure (CVE-ID: CVE-2021-34491)

The vulnerability allows a local user to gain access to potentially sensitive information.

The vulnerability exists due to excessive data output by the application in the Win32k. A local user can gain unauthorized access to sensitive information on the system.

3) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2021-34449)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to application does not properly impose security restrictions in the Win32k, which leads to security restrictions bypass and privilege escalation.

Remediation

Install update from vendor's website.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34516
• https://www.zerodayinitiative.com/advisories/ZDI-21-895/
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34491
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34449