Microsoft released November 2020 security updates on Tuesday which fix 112 vulnerabilities ranging from simple spoofing attacks to remote code execution, including 17 critical vulnerabilities, 93 important vulnerabilities, and two low vulnerabilities. All users are advised to install updates without delay.
These vulnerabilities affect Azure DevOps, Azure Sphere, Common Log File System Driver, Microsoft Browsers, Microsoft Dynamics, Microsoft Exchange Server, Microsoft Graphics Component, Microsoft Office, Microsoft Office SharePoint, Microsoft Scripting Engine, Microsoft Teams, Microsoft Windows, Microsoft Windows Codecs Library, Visual Studio, Windows Defender, Windows Kernel, Windows NDIS, Windows Update Stack, and Windows WalletService.
Description of Critical and Important Vulnerabilities
Some critical and important vulnerabilities are described as follows:
- Windows Kernel Local Privilege Escalation Vulnerability (CVE-2020-17087)
On November 2, 2020, Google Project Zero published an article about the Windows cng.sys privilege escalation vulnerability (CVE-2020-17087). The vulnerability allows attackers without authentication to trick users into running crafted malicious programs to escalate privileges. At that time, CVE-2020-17087 had been exploited in the wild, and Microsoft had not released relevant patches.
In these updates, the vulnerability is fixed. Affected users are advised to install the patches.
According to Microsoft, the CVSS base score of this important vulnerability is 3.0 7.8/7.2:
- Windows Network File System (NFS) Vulnerabilities (CVE-2020-17051, CVE-2020-17056)
CVE-2020-17051 is a remote code execution vulnerability on the nfssvr.sys driver, which can cause an immediate BSOD (Blue Screen of Death).
CVE-2020-17056 is a remote kernel data read vulnerability on the nfssvr.sys driver, which can lead to an address space layout randomization (ASLR) bypass.
The combination of these two vulnerabilities dramatically increases the likelihood of a remote exploit when used on the Windows Server to bypass exploit mitigations.
NFS is used to share files in the Windows and Unix/Linux environments.
According to Microsoft, the CVSS base score of this critical vulnerability (CVE-2020-17051) is 3.0 9.8/8.5:
According to Microsoft, the CVSS base score of this important vulnerability (CVE-2020-17056) is 3.0 5.5/4.8:
- Microsoft Exchange Server Vulnerabilities (CVE-2020-17083, CVE-2020-17084, CVE-2020-17085)
CVE-2020-17083 and CVE-2020-17084 are remote code execution vulnerabilities on the Microsoft Exchange Server. CVE-2020-17085 is a denial-of-service vulnerability.
According to Microsoft, the CVSS base score of these important vulnerabilities are as follows:
CVE-2020-17083 CVSS:3.0 5.5/4.8
CVE-2020-17084 CVSS:3.0 8.5/7.4
CVE-2020-17085 CVSS:3.0 6.2/5.4
- Windows Hyper-V Security Feature Bypass Vulnerability (CVE-2020-17040)
Hyper-V is prone to a security feature bypass vulnerability that is easy to exploit without requiring privileges and user interaction.
According to Microsoft, the CVSS base score of this important vulnerability is 3.0 6.5/5.7:
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