Microsoft Patch Tuesday – October 2023

Microsoft addresses 103 CVEs with 12 rated as critical and 91 rated as important and including two vulnerabilities that were exploited in the wild.

This month’s update includes patches for:

• Active Directory Domain Services
• Azure
• Azure DevOps
• Azure Real Time Operating System
• Azure SDK
• Client Server Run-time Subsystem (CSRSS)
• Microsoft Common Data Model SDK
• Microsoft Dynamics
• Microsoft Exchange Server
• Microsoft Graphics Component
• Microsoft Office
• Microsoft QUIC
• Microsoft WDAC OLE DB provider for SQL
• Microsoft Windows Media Foundation
• Microsoft Windows Search Component
• Microsoft WordPad
• SQL Server
• Skype for Business
• Windows Active Template Library
• Windows AllJoyn API
• Windows Client/Server Runtime Subsystem
• Windows Common Log File System Driver
• Windows Container Manager Service
• Windows DHCP Server
• Windows Deployment Services
• Windows Error Reporting
• Windows HTML Platform
• Windows IIS
• Windows IKE Extension
• Windows Kernel
• Windows Layer 2 Tunneling Protocol
• Windows Mark of the Web (MOTW)
• Windows Message Queuing
• Windows Microsoft DirectMusic
• Windows Mixed Reality Developer Tools
• Windows NT OS Kernel
• Windows Named Pipe File System
• Windows Power Management Service
• Windows RDP
• Windows Remote Procedure Call
• Windows Resilient File System (ReFS)
• Windows Runtime C++ Template Library
• Windows Setup Files Cleanup
• Windows TCP/IP
• Windows TPM
• Windows Virtual Trusted Platform Module
• Windows Win32K

Microsoft WordPad Information Disclosure Vulnerability

CVE-2023-36563 is an information disclosure vulnerability in Microsoft WordPad with a CVSSv3 score of 6.5. It was exploited in the wild as a zero-day and was publicly disclosed prior to the October 2023 Patch Tuesday release.

An unauthenticated, remote attacker could exploit this vulnerability using social engineering to convince a target to open a link or download a malicious file and run it on the vulnerable system. Alternatively, an attacker could execute a specially crafted application to exploit the flaw after gaining access to a vulnerable system. Successful exploitation could lead to the disclosure of New Technology LAN Manager (NTLM) hashes.

This is the third zero-day vulnerability patched in 2023 that could result in the unauthorized disclosure of NTLM hashes. In March, Microsoft patched CVE-2023-23397, a Microsoft Outlook elevation of privilege vulnerability, and in September, Microsoft patched CVE-2023-36761, an information disclosure vulnerability in Microsoft Word. It is unclear if all three of these vulnerabilities were exploited by the same attackers.

Skype for Business Elevation of Privilege Vulnerability

CVE-2023-41763 is an EoP vulnerability in Skype for Business with a CVSSv3 score of 5.3 and rated important. An unauthenticated, remote attacker could exploit this vulnerability by sending a specially crafted network call to a vulnerable Skype for Business server. Successful exploitation would result in the disclosure of sensitive information, which could be used to gain access to internal networks.

This vulnerability was exploited in the wild according to Microsoft, though no details have been shared at the time this blog post was published. However, this vulnerability is noted to have been publicly disclosed previously.

Microsoft Message Queuing Remote Code Execution Vulnerability

CVE-2023-35349 is a RCE vulnerability in the Microsoft Message Queuing (MSMQ) component of Windows operating systems with a CVSSv3 score of 9.8 and rated critical. An unauthenticated, remote attacker could exploit this vulnerability by sending a specially crafted packet to a vulnerable target.

In addition to CVE-2023-35349, Microsoft has patched 15 additional RCE vulnerabilities in MSMQ. While CVE-2023-36697 was also rated critical, successful exploitation requires either user interaction or for the attacker to be authenticated as a domain user and to have compromised a MSMQ server within the target network.

CVE-2023-35349 and CVE-2023-36697 are two of several critical RCE vulnerabilities in MSMQ that have been patched this year. CVE-2023-35385, CVE-2023-36910 and CVE-2023-36911 were patched in August, CVE-2023-32057 in July and CVE-2023-21554 in April.

For a system to be vulnerable to these vulnerabilities, the MSMQ service must be added and enabled. According to Microsoft, if the service is enabled on a Windows installation, a service named “Message Queueing” will be running on TCP port 1801.

Windows IIS Server Elevation of Privilege Vulnerability

CVE-2023-36434 is an EoP vulnerability in Windows IIS server with a CVSSv3 score of 9.8 and rated as important. According to Microsoft, exploitation of this vulnerability is achieved by an attacker brute forcing a user’s login credentials. Because the chances of success can vary greatly and are less likely when strong passwords are in place, Microsoft’s severity rating is important, despite the critical CVSS score.

Microsoft Office Elevation of Privilege Vulnerability

CVE-2023-36569 is an EoP vulnerability in Microsoft Office with a CVSSv3 score of 8.4 and is rated as important. Successful exploitation of this vulnerability would provide an attacker with SYSTEM level privileges. Microsoft notes that this vulnerability is less likely to be exploited and that the preview pane is not an attack vector for exploiting this vulnerability.

Microsoft Exchange Server Remote Code Execution Vulnerability

CVE-2023-36778 is a RCE vulnerability in Microsoft Exchange Server with a CVSSv3 score of 8 and is rated as important. A local, authenticated attacker could exploit this vulnerability through a remote PowerShell session with the target server. The vulnerability is caused by improper validation of cmdlet arguments within Microsoft Exchange Server.

HTTP/2 Rapid Reset Attack

CVE-2023-44487 is a denial of service (DoS) vulnerability affecting HTTP/2 web servers that was exploited in the wild. While this vulnerability was not exclusive to affecting Microsoft servers, patches were made available to address this vulnerability in multiple versions of Windows, including Server Core installations.

This vulnerability was exploited against multiple targets in a distributed denial of service (DDoS) attack and was first observed by Cloudflare on August 25 and Edgio on August 28th. Cloudflare worked with both Google and Amazon AWS who have acknowledged that additional mitigations are in place to address this vulnerability. As noted in Cloudflare’s technical blog post, the underlying vulnerability is in HTTP/2 and other vendors utilizing HTTP/2 may be affected by the vulnerability.

Windows Server 2012 and 2012 R2 End of Life

Microsoft announced that Windows Server 2012 and Windows Server 2012 R2 has reached its end of life as of October 10, 2023. This means that users of these versions of Windows Server will no longer receive security updates and should upgrade to a supported version as soon as possible.

Patch Release Summary