Microsoft: New Critical Windows SMBv3 RCE Zero-day vulnerability

Η Microsoft released details on one Windows vulnerability which has not been corrected and is located in Server Message Block 3.0 (SMBv3) communication protocol, mentioned as part of patch Tuesday for March 2020.

Vulnerability is called CVE-2020-0796 and affects only Windows 10 Version and Windows Server Version 1903.

Wormable Windows SMBv3

As mentioned above, vulnerability is detected in the SMBv3 protocol. An attacker could take advantage of it by sending one a specially designed package on a vulnerable SMBv3 Server.

Still, no technical details on the vulnerability have been revealed. However, the companies security Fortinet and Tenable provide some summary reports.

The vulnerability relates to how the software handles it malicious request created via a compressed data packet. An unauthorized attacker could exploit the vulnerability and get him control of systemic of the victim.

“To exploit vulnerability against an SMB server, an unauthorized attacker could send a specially designed package to a targeted SMBv3 server. To exploit vulnerability against an SMB Client, an attacker must configure a malicious SMBv3 Server and persuade an user to connect with him ”, he says Microsoft.

Versions affected

This vulnerability affects versions Windows 10 desktop version and Windows Server 1903.

• Window 10 version 1903 for 32 bit systems
• Windows 10 version 1903 for x64-based systems
• Window 10 version 1903 for ARM64-based systems
• Windows Server 1903 (Server Core installation)
• Windows 10 version 1909 for 32 bit systems
• Windows 10 version 1909 for x64-based systems
• Windows 10 version 1909 for ARM64-based systems
• Window Server, version 1909 (Server Core installation)

Currently, no patch available to correct the vulnerability. Until then, SMBv3 will remain vulnerable.

Microsoft suggested to administrators servers to disable SMBv3 compression to prevent intruders from exploiting vulnerability.

Also, the blocking TCP 445 port can prevent intruders from attaching to vulnerable machines.

The error is considered critical. In the past, many hackers had exploited such vulnerabilities to realize attacks.