Pierluigi Paganini January 13, 2021

Microsoft Patch Tuesday security updates for January 2021 address 83 vulnerabilities, including a critical flaw actively exploited in the wild.

Microsoft Patch Tuesday security updates for January 2021 fix 83 security vulnerabilities in multiple products, including Microsoft Windows, Edge (EdgeHTML-based), ChakraCore, Office and Microsoft Office Services and Web Apps, Visual Studio, Microsoft Malware Protection Engine, .NET Core, ASP .NET, and Azure. 10 of these flaws are rated as Critical and 73 are rated as Important in severity. Seven of the addressed flaws were submitted through the ZDI program.

The IT giant has addressed a zero-day RCE flaw in Microsoft Defender, tracked as CVE-2021-1647, that resides in the Malware Protection Engine component (mpengine.dll).

The Microsoft Malware Protection Engine component provides the scanning, detection, and cleaning capabilities for Microsoft antimalware software.

Microsoft did not disclose details on the attacks in the wild that exploited this flaw.

The remaining critical remote code execution vulnerabilities addressed by the company are listed below:

The remaining vulnerabilities addressed by Microsoft Patch Tuesday for January are rated as “important” and are code execution, information disclosure, and denial-of-service issues.

Another interesting flaw addressed by Microsoft is a Microsoft splwow64 elevation of privilege vulnerability, tracked as CVE-2021-1648.

The flaw was discovered by the popular Google Project Zero expert Maddie Stone.

“While this issue is labeled as an elevation of privilege, it can also be exploited to disclose information. The type of information that could be disclosed if an attacker successfully exploited this vulnerability is uninitialized memory.” reads the security advisory published by Microsoft.

“This issue has been publicly disclosed by Google Project Zero (PZ2096) and the Zero Day Initiative (ZDI-CAN-11349 through 11351).”

As usually let me suggest reading the security update review published by the Zero Day Initiative that also highlights the importance of the following flaws addressed by Microsoft:

• CVE-2021-1677 – Azure Active Directory Pod Identity Spoofing Vulnerability
• CVE-2021-1674 – Windows Remote Desktop Protocol Core Security Feature Bypass Vulnerability

“In looking at the Important-rated bugs that could allow RCE, the SharePoint bug should not be ignored. It does require authentication, but it could allow an authenticated user to take complete control of the system.” states ZDI.

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Pierluigi Paganini

(SecurityAffairs – hacking, Microsoft Patch Tuesday)

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