PT-2021-5655 · Microsoft · Windows 10

Socram8888 · Published 2021-12-15 · Updated 2022-03-29 · CVE-2021-45100

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Name of the Vulnerable Software and Affected Versions ksmbd server versions 3.4.2 and earlier Linux kernel versions 5.15.8 and earlier

Description The issue is related to the ksmbd server's implementation of the SMB protocol, specifically when using the SMB 3.1.1 protocol. The server sets the SMB2 GLOBAL CAP ENCRYPTION flag, which is a violation of the SMB protocol specification. As a result, Windows 10 detects this protocol violation and disables encryption, causing the server to communicate in cleartext even though encryption has been enabled. This could allow a remote attacker to gain unauthorized access to protected information.

Recommendations For ksmbd server versions 3.4.2 and earlier, consider disabling the use of the SMB2 GLOBAL CAP ENCRYPTION flag when using the SMB 3.1.1 protocol until a patch is available. For Linux kernel versions 5.15.8 and earlier, update to a version that includes the fix for this issue. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Cleartext Transmission of Sensitive Information

Weakness Enumeration

CWE-319

Related Identifiers

BDU:2022-00093

CVE-2021-45100

MGASA-2022-0021

MGASA-2022-0022

Affected Products

Windows 10

References · 28

• https://github.com/cifsd-team/ksmbd/pull/551 · Patch
• https://ubuntu.com/security/CVE-2021-45100 · Vendor Advisory
• https://bdu.fstec.ru/vul/2022-00093 · Security Note
• https://cve.org/CVERecord?id=CVE-2021-45100 · Security Note
• https://advisories.mageia.org/MGASA-2022-0021.html · Security Note
• https://osv.dev/vulnerability/MGASA-2022-0021 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-45100 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-45100 · Vendor Advisory
• https://advisories.mageia.org/MGASA-2022-0022.html · Security Note
• https://osv.dev/vulnerability/MGASA-2022-0022 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-45100 · Security Note
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-45100 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-45100 · Vendor Advisory
• https://github.com/cifsd-team/ksmbd/issues/550 · Note
• https://bugs.mageia.org/show_bug.cgi?id=29879 · Note