Patch Tuesday - April 2022

From Defender to Windows, Office to Azure, this month’s Patch Tuesday has a large swath of Microsoft’s portfolio getting vulnerabilities fixed. 119 CVEs were addressed today, not including the 26 Chromium vulnerabilities that were fixed in the Edge browser.

One of these has been observed being exploited in the wild: CVE-2022-24521, reported to Microsoft by the National Security Agency, affects the Common Log File System Driver in all supported versions of Windows and allows attackers to gain additional privileges on a system they already have local access to. Another local privilege escalation (LPE), CVE-2022-26904 affecting the Windows User Profile Service, had been publicly disclosed but not reported as already being exploited – it’s harder for attackers to leverage as it relies on winning a race condition, which can be tricky to reliably achieve.

LPEs don’t always get the same attention that remote code execution (RCE) vulnerabilities do, but they can be a great help to attackers after they gain an initial foothold. These two categories dominate this month’s vulnerabilities, with 55 LPEs and 47 RCEs getting patched. 10 of the RCEs are considered “Critical,” affecting Windows Hyper-V (CVE-2022-22008, CVE-2022-23257, CVE-2022-24537); Windows SMB Client (CVE-2022-24500, CVE-2022-24541); Windows Network File System (CVE-2022-24491 and CVE-2022-24497); LDAP (CVE-2022-26919); Microsoft Dynamics (CVE-2022-23259); and the Windows RPC Runtime (CVE-2022-26809).

On the Office side of the house, Skype for Business Server was patched for spoofing (CVE-2022-26910) and information disclosure (CVE-2022-26911) vulnerabilities. Two RCEs affecting Excel (CVE-2022-24473 and CVE-2022-26901) were fixed, as well as a spoofing vulnerability in SharePoint Server (CVE-2022-24472).

With so many vulnerabilities to manage, it can be difficult to prioritize. Thankfully, most of this month’s CVEs can be addressed by patching the core OS. Administrators should first focus on updating any public-facing servers before moving on to internal servers and then client systems. The SMB Client vulnerabilities can also be mitigated by blocking port 445/tcp at the network perimeter – victims need to be enticed to connect to a malicious SMB server, and this would help against Internet-based attackers. Of course, this won’t help much if the malicious system was set up within the perimeter.

For any readers who enjoy deeper dives into vulnerabilities and exploits, Rapid7’s Jake Baines has a technical writeup of CVE-2022-24527, an LPE he discovered in the Connected Cache component of Microsoft Endpoint Manager that got fixed today. Check it out!

Summary charts

Summary tables

Azure Vulnerabilities

Browser Vulnerabilities

Developer Tools Vulnerabilities

Microsoft Dynamics Vulnerabilities

Microsoft Office Vulnerabilities

SQL Server Vulnerabilities

System Center Vulnerabilities

Windows Vulnerabilities

Windows ESU Vulnerabilities

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