Patch Tuesday (January 2021): Microsoft patches 83 vulnerabilities, including a Zero-Day
10 bugs have been rated as “critical” and 73 as “important”
Marking the first Patch Tuesday of 2021, Microsoft has released updates to its operating systems and other software, patching over 80 security holes (including one currently exploited by malicious hackers). Ten of the bugs received the “critical” ranking, indicating that they could be abused by malware or threat actors to gain remote control over unpatched systems with little to no user intervention.
The January 2020 Patch Tuesday addressed vulnerabilities found in Windows, Microsoft Malware Protection Engine, Microsoft Edge, Microsoft Office, Microsoft Windows Codecs Library, Azure, SQL Server, Visual Studio, .NET Core, .NET Repository, and ASP.NET.
Zero-Day in Microsoft Defender
One of the software flaws (CVE-2021-1647) found in Microsoft Defender is already being actively abused. Since the vendor has recently stopped supplying a high amount of information in their vulnerability advisories, it’s quite unclear how attackers could be leveraging it. Nonetheless, the RCE bug may enable threat actors to run code on compromised computers by tricking users into downloading and opening a malicious document on a machine where Defender is installed.
Microsoft believes that the method is not practical in all cases, and is therefore considered to be at a proof-of-concept stage, despite misuse being observed in the wild. For more successful assaults, however, the code may be improved.
The software giant also issued updates for the Microsoft Malware Protection Engine (version 1.1.17700.4 or later) to prevent potential attacks, which would entail little user intervention.
You can follow the instructions in this guide by Bleeping Computer to check the installed version of your Microsoft Defender engine.
Elevation of Privilege vulnerability
In the Windows splwow64 service, Microsoft has patched a security bug that could be exploited to elevate the rights of an intruder. Last month, the details on this bug (tracked as CVE-2021-1648) were made public. However, the flaw was not exploited in the wild, according to Microsoft, despite the information being publicly accessible.
Windows RDP Core Security Feature Bypass Vulnerability
CVE-2021-1674 is a Windows Remote Desktop Protocol (RDP) flaw that can be abused by an attacker with a privileged account. The bug was not officially revealed to have been abused, yet, RDP has always been a preferred attack entry point used by malicious actors.
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As always, Heimdal™ urges administrators to install this month’s updates to prevent potential disruptions in the event that any of these bugs are utilized by cybercriminals.
With automated updates activated, our customers who use Heimdal™ Patch & Asset Management can relax knowing that they are safe.
Every month, almost 50% of Heimdal™’s Business customers patch their Microsoft applications within 3 days upon release. The rest of them tend to pause the process of patching according to their own timetable.
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Additional Patch Management resources:
- Microsoft’s official Security Update Guide portal
- Past Patch Tuesday updates dissected on Heimdal™’s blog
- What is Patch Management?
- Software Rot and Cybersecurity: Why Code Degradation Is Crucial to Business Safety
- Patch Management Best Practices to Safeguard Your Business in 2021
- 7 Open Source Patch Management Software to Bootstrap Your Business
- 5 Common Myths about Software Updates You Need to Know
- Patching Your Software Alone Is A Hassle. Not Patching Is A Risk