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CVE-2020-0796: Microsoft SMBv3 Remote Code Execution Vulnerability

CVE-2020-0796 is rated critical with a CVSS v3.1 base score of 10.0 and affects Microsoft SMBv3, along with 4 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-02-10, which means exploitation in the wild has been observed.

Vulnerability description

A remote code execution vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests, aka 'Windows SMBv3 Client/Server Remote Code Execution Vulnerability'.

Severity breakdown

CVSS v3.1 10.0: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

Affected products

• Microsoft Windows 10 1903: all versions listed by NVD
• Microsoft Windows 10 1909: all versions listed by NVD
• Microsoft Windows Server 1903: all versions listed by NVD
• Microsoft Windows Server 1909: all versions listed by NVD

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796
• http://packetstormsecurity.com/files/156731/CoronaBlue-SMBGhost-Microsoft-Windows-10-SMB-3.1.1-Proof-Of-Concept.html
• http://packetstormsecurity.com/files/156732/Microsoft-Windows-SMB-3.1.1-Remote-Code-Execution.html
• http://packetstormsecurity.com/files/156980/Microsoft-Windows-10-SMB-3.1.1-Local-Privilege-Escalation.html
• http://packetstormsecurity.com/files/157110/SMBv3-Compression-Buffer-Overflow.html
• http://packetstormsecurity.com/files/157901/Microsoft-Windows-SMBGhost-Remote-Code-Execution.html
• http://packetstormsecurity.com/files/158054/SMBleed-SMBGhost-Pre-Authentication-Remote-Code-Execution-Proof-Of-Concept.html
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-0796