Rewterz Threat Advisory – SMBleed: A New Critical Vulnerability Affects Windows SMB Protocol

Severity

High

Analysis Summary

A new critical vulnerability is affecting the Server Message Block (SMB) protocol that could allow attackers to leak kernel memory remotely, and when combined with a previously disclosed “wormable” bug, the flaw can be exploited to achieve remote code execution attacks on unpatched systems running Windows 10. 
Dubbed “SMBleed” (CVE-2020-1206) by cybersecurity firm ZecOps, the flaw resides in SMB’s decompression function — the same function as with SMBGhost or EternalDarkness bug (CVE-2020-0796), which came to light three months ago, potentially opening vulnerable Windows systems to malware attacks that can propagate across networks. An attacker who successfully exploited the vulnerability could obtain information to further compromise the user’s system. 

• To exploit the vulnerability against a server, an unauthenticated attacker could send a specially crafted packet to a targeted SMBv3 server. 
• To exploit the vulnerability against a client, an unauthenticated attacker would need to configure a malicious SMBv3 server and convince a user to connect to it.

Impact

• Remote Code Execution
• Information Disclosure
• System Compromise
• Possible Network-wide attack

Affected Products

Windows 10 versions 1903 and 1909

Remediation

Updates have been released.
See Microsoft’s security guidance addressing SMBleed and SMBGhost in Windows 10 version 1909 and 1903 and Server Core:

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1206

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796