Summary
*** Patch Windows 10 and affected Windows Server 2019 systems IMMEDIATELY, even where there is a potential business impact (unscheduled maintenance). Notify security@berkeley.edu if you anticipate delays in patching. ***
A patch is available (KB4551762) [1] for a remote code execution vulnerability for how Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests. [2, 3]
Impact
Vulnerable
- Microsoft Windows 10 version 1903
- Microsoft Windows 10 version 1909
- Microsoft Windows Server 2019 version 1903
- Microsoft Windows Server 2019 version 1909
Recommendations
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Patch vulnerable systems IMMEDIATELY.
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Ensure your system is receiving automatic updates - if not apply the patch manually.
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Prioritize patching systems that connect from off-campus through VPNs or proxies.
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If immediate patching is not an option and SMBv3 compression is not necessary, disable SMBv3 compression [4], or restrict access to the host by creating a firewall rule to block SMB traffic.
References
[1] https://support.microsoft.com/en-us/help/4551762/windows-10-update-kb4551762
[2] https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796
[3] https://www.zdnet.com/article/microsoft-patches-smbv3-wormable-bug-that-leaked-earlier-this-week/
[4] https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/adv200005