Microsoft Patch Tuesday: 14th December 2021

The latest release of Microsoft Patch Tuesday is now active with the security update offering 67 overall vulnerabilities categorised as; 7 critical and 60 important, with 6 publicly disclosed and 1 seen being exploited in the wild.

This month release covers security updates for components including:
  • Windows AppX Installer
  • SharePoint Server
  • Visual Studio
  • Visual Studio Code
  • PowerShell
  • Microsoft Office
  • Edge Browser
  • Microsoft Defender for IoT

Critical Updates

CVE-2021-43890: Windows AppX Installer Spoofing Vulnerability

The AppX Installer service vulnerability affecting Windows systems is the only flaw this month that is being actively exploited in the wild. This vulnerability, labelled critical, is being exploited to spread the Emotet/Trickbot/Bazaloader malware types. Microsoft commented on this, saying: “An attacker could craft a malicious attachment to be used in phishing campaigns. The attacker would then have to convince the user to open the specially crafted attachment”.

CVE-2021-41333: Windows Print Spooler Elevation of Privilege Vulnerability

Hackers could potentially gain elevated privileges on an affected system through the Windows Print Spool service. This is one of the 6 vulnerabilities that has been publicly released and has a low attack complexity, meaning it is easier to exploit.

CVE-2021-43880: Windows Mobile Device Management Elevation of Privilege Vulnerability

Similar to the previous flaw, this publicly disclosed vulnerability could allow for unauthorised privilege escalation on a mobile device using Windows MDM. This vulnerability also allows local hackers to delete files located on the system.

Software patches are essential to keeping any device secure from potential threats. We highly recommend that you update these as soon as possible given the high-risk excel and VM vulnerabilities posing serious security concerns.

For a full list of this month’s updates please see the links below:

Patch Tuesday release notes:

Security update guide:

Ironshare – Security Simplified