CVE-2018-8449 — Device Guard Security Feature Bypass Vulnerability

Executive Summary

A security feature bypass exists when Device Guard incorrectly validates an untrusted file. An attacker who successfully exploited this vulnerability could make an unsigned file appear to be signed. Because Device Guard relies on the signature to determine the file is non-malicious, Device Guard could then allow a malicious file to execute. In an attack scenario, an attacker could make an untrusted file appear to be a trusted file. The update addresses the vulnerability by correcting how Device Guard handles untrusted files.

Overview

5.3

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

More Likely

MS Exploit Likelihood

Category Security Feature Bypass

Released Sep 11 2018

Last Updated Sep 11 2018

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

CVSS Vector

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

Low

INTEGRITY

Low

AVAILABILITY

Low

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.8

EPSS Score

No EPSS score available for this CVE.

View on FIRST.org

Affected Products

14 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 for 32-bit Systems	`4457132 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 for x64-based Systems	`4457132 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1607 for 32-bit Systems	`4457131 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1607 for x64-based Systems	`4457131 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1703 for 32-bit Systems	`4457138 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1703 for x64-based Systems	`4457138 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for 32-bit Systems	`4457142 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for x64-based Systems	`4457142 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for 32-bit Systems	`4457128 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for x64-based Systems	`4457128 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2016	`4457131 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2016 (Server Core installation)	`4457131 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server, version 1709 (Server Core Installation)	`4457142 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server, version 1803 (Server Core Installation)	`4457128 (Security Update)`	Important	Security Feature Bypass	Yes

Patches

5 patches

Article	Type	Restart
`4457132`	Security Update	Yes
`4457131`	Security Update	Yes
`4457138`	Security Update	Yes
`4457142`	Security Update	Yes
`4457128`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

James Forshaw of Google Project Zero

References

MSRC Advisory MITRE NVD