ADV190005 — Guidance to adjust HTTP/2 SETTINGS frames

Executive Summary

Executive Summary Microsoft is aware of a potential condition which can be triggered when malicious HTTP/2 requests are sent to a Windows Server with the http.sys service enabled. This could temporarily cause the system CPU usage to spike to 100% until the malicious connections are killed by http.sys. The HTTP/2 specification allows clients to specify any number of SETTINGS frames with any number of SETTINGS parameters. In some situations, excessive settings can cause services to become unstable and may result in a temporary CPU usage spike until the connection timeout is reached and the connection is closed. To address this issue, Microsoft has added the ability to define thresholds on the number of HTTP/2 SETTINGS included in a request. These thresholds must be defined by the system administrator. They are not preset by Microsoft. Recommended Actions Install the February non-security update. Customers should review Knowledge Base Article 4491420 and take appropriate action.

Overview

Unknown

MS Severity

Not Exploited

MS Exploit Status

Not Found

MS Exploit Likelihood

Category Defense in Depth

Released Feb 12 2019

Last Updated Feb 12 2019

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

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 Version 1607 for 32-bit Systems	`4487006 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1607 for x64-based Systems	`4487006 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1703 for 32-bit Systems	`4487011 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1703 for x64-based Systems	`4487011 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1709 for 32-bit Systems	`4487021 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4487021 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1709 for x64-based Systems	`4487021 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1803 for 32-bit Systems	`4487029 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4487029 (Update)`	Unknown	Defense in Depth	Yes
Windows 10 Version 1803 for x64-based Systems	`4487029 (Update)`	Unknown	Defense in Depth	Yes
Windows Server 2016	`4487006 (Update)`	Unknown	Defense in Depth	Yes
Windows Server 2016 (Server Core installation)	`4487006 (Update)`	Unknown	Defense in Depth	Yes
Windows Server, version 1709 (Server Core Installation)	`4487021 (Update)`	Unknown	Defense in Depth	Yes
Windows Server, version 1803 (Server Core Installation)	`4487029 (Update)`	Unknown	Defense in Depth	Yes

Patches

4 patches

Article	Type	Restart
`4487006`	Update	Yes
`4487011`	Update	Yes
`4487021`	Update	Yes
`4487029`	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

Gal Goldshtein of F5 Networks

References

MSRC Advisory MITRE NVD