Microsoft Security Advisory CVE-2019-0657: PowerShell Core Domain Spoofing Vulnerability
Executive Summary
Microsoft is releasing this security advisory to provide information about a vulnerability in PowerShell Core 6.1 and 6.2. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Microsoft is aware of a domain spoofing vulnerability in PowerShell Core which causes the meaning of a URI to change when International Domain Name encoding is applied. An attacker who successfully exploited the vulnerability could redirect a URI.
The security update addresses the vulnerability by disallowing certain Unicode characters from the URI.
System administrators are advised to update PowerShell Core to an unaffected version version (see affected software.)
Discussion
Please use PowerShell/PowerShell#8917 for discussion of this advisory.
Please use dotnet/corefx#35265 for discussion of the .NET Core aspects this advisory.
Run pwsh -v, then, check the version in the table in Affected Software to see if your version of PowerShell Core is affected.
If you are running a version of PowerShell Core where the executable is not pwsh or pwsh.exe, then you are affected. This only existed for preview version of 6.0.
If you have found a potential security issue in PowerShell Core,
please email details to secure@microsoft.com.
Support
You can ask questions about this issue on GitHub in the PowerShell organization.
This is located at https://github.com/PowerShell/.
The Announcements repo (https://github.com/PowerShell/Announcements)
will contain this bulletin as an issue and will include a link to a discussion issue where you can ask questions.
What if the update breaks my script or module?
You can uninstall the newer version of PowerShell Core and install the previous version of PowerShell Core.
This should be treated as a temporary measure.
Therefore, the script or module should be updated to work with the patched version of PowerShell Core.
Acknowledgments
Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.
Microsoft Security Advisory CVE-2019-0657: PowerShell Core Domain Spoofing Vulnerability
Executive Summary
Microsoft is releasing this security advisory to provide information about a vulnerability in PowerShell Core 6.1 and 6.2. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Microsoft is aware of a domain spoofing vulnerability in PowerShell Core which causes the meaning of a URI to change when International Domain Name encoding is applied. An attacker who successfully exploited the vulnerability could redirect a URI.
The security update addresses the vulnerability by disallowing certain Unicode characters from the URI.
System administrators are advised to update PowerShell Core to an unaffected version version (see affected software.)
Discussion
Please use PowerShell/PowerShell#8917 for discussion of this advisory. Please use dotnet/corefx#35265 for discussion of the .NET Core aspects this advisory.
Affected Software
The vulnerability affects PowerShell Core prior to the following versions:
Advisory FAQ
How do I know if I am affected?
If all of the following are true:
pwsh -v, then, check the version in the table in Affected Software to see if your version of PowerShell Core is affected.pwshorpwsh.exe, then you are affected. This only existed for preview version of6.0.How do I update to an unaffected version?
Follow the instructions at Installing PowerShell Core to install the latest version of PowerShell Core.
Other Information
Reporting Security Issues
If you have found a potential security issue in PowerShell Core, please email details to secure@microsoft.com.
Support
You can ask questions about this issue on GitHub in the PowerShell organization. This is located at https://github.com/PowerShell/. The Announcements repo (https://github.com/PowerShell/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue where you can ask questions.
What if the update breaks my script or module?
You can uninstall the newer version of PowerShell Core and install the previous version of PowerShell Core. This should be treated as a temporary measure. Therefore, the script or module should be updated to work with the patched version of PowerShell Core.
Acknowledgments
Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.
See acknowledgments for more information.
External Links
CVE-2019-0657
Revisions
V1.0 (Feb 19, 2019): Advisory published.
Version 1.0 Last Updated 2019-02-19