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Microsoft today finally released an emergency software update to patch the recently disclosed very dangerous vulnerability in SMBv3 protocol that could let attackers launch wormable malware, which can propagate itself from one vulnerable computer to another automatically.

The vulnerability, tracked as CVE-2020-0796, in question is a remote code execution flaw that impacts Windows 10 version 1903 and 1909, and Windows Server version 1903 and 1909.

Server Message Block (SMB), which runs over TCP port 445, is a network protocol that has been designed to enable file sharing, network browsing, printing services, and interprocess communication over a network.

The latest vulnerability, for which a patch update (KB4551762) is now available on the Microsoft website, exists in the way SMBv3 protocol handles requests with compression headers, making it possible for unauthenticated remote attackers to execute malicious code on target servers or clients with SYSTEM privileges.

Compression headers is a feature that was added to the affected protocol of Windows 10 and Windows Server operating systems in May 2019, designed to compress the size of messages exchanged between a sever and clients connected to it.

images from Hacker News