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Microsoft Security Advisory CVE-2019-1075: ASP.NET Core Spoofing Vulnerability #12007
Comments
How does this apply to Azure WebApps? What is the recommended way to protect an app running on Azure WebApp. The latest runtime I see installed is 2.2.5. |
The way Azure web apps proxies requests is different to how IIS and Windows hosting does it, and the issue shouldn't arise. |
@blowdart If that is the case, could you update the advisory to include this as a mitigating factor? |
I'll do some more investigation first to be 100% sure. |
Is there any information whether Kestrel in ASP.NET Core 2.1 hosted behind reverse proxies like NginX or AWS ALB affected (on Linux, no Windows/IIS)? I'm also a bit unsure how to understand CVE-2019-1075 in general. |
Thank you for contacting us. Due to a lack of activity on this discussion issue we're closing it in an effort to keep our backlog clean. If you believe there is a concern related to the ASP.NET Core framework, which hasn't been addressed yet, please file a new issue. This issue will be locked after 30 more days of inactivity. If you still wish to discuss this subject after then, please create a new issue! |
Microsoft Security Advisory CVE-2019-1075: ASP.NET Core Spoofing Vulnerability
Executive summary
Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET Core 2.1 and 2.2. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.
Microsoft is aware of a spoofing vulnerability that exists in ASP.NET Core that could lead to an open redirect. An attacker who successfully exploited the vulnerability could redirect a targeted user to a malicious website.
To exploit the vulnerability, an attacker could send a link that has a specially crafted URL and convince the user to click the link.
The update addresses the vulnerability by correcting how ASP.NET Core parses URLs.
Original Announcement
The original announcement for this issue can be found at aspnet/Announcements#373
Mitigation factors
Microsoft has not identified any mitigating factors for this vulnerability.
Affected software
Any ASP.NET Core based application that uses any of following vulnerable packages:
2.2.0
2.2.6
2.2.0 - 2.2.5
2.2.6
2.2.0 - 2.2.5
2.2.6
Advisory FAQ
How do I know if I am affected?
The affected assemblies are part of .NET Core. If you are running a vulnerable version of .NET Core you may be affected.
How do I fix the issue?
To fix the issue please install the latest version of .NET Core. If you have multiple versions of .NET Core installed you will need to install multiple runtimes, or SDKs depending on what you have installed.
If you have .NET Core 2.0 or greater installed, you can list the versions you have installed by running the
dotnet --info
command. You will see output like the following;If you have both 2.1 and 2.2, you need to install updates for both versions.
Once you have installed the updated runtime or SDK, restart your apps for the update to take effect.
If you have pinned your application to a specific version of the runtime, you must update your app, recompile and redeploy it for the update to take effect.
Other Information
Reporting Security Issues
If you have found a potential security issue in .NET Core, please email details to secure@microsoft.com. Reports may qualify for the .NET Core Bug Bounty. Details of the .NET Core Bug Bounty including terms and conditions are at https://aka.ms/corebounty.
Support
You can ask questions about this issue on GitHub in the .NET Core or ASP.NET Core organizations. These are located at https://github.com/dotnet/ and https://github.com/aspnet/, respectively. The Announcements repo for each product (https://github.com/dotnet/Announcements and https://github.com/aspnet/Announcements) will contain this bulletin as an issue and will include a link to a discussion issue. You can ask questions in the discussion issue.
Disclaimer
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
Acknowledgements
Reported through Datalust
External Links
CVE-2019-1075
Revisions
V1.0 (July 9, 2019): Advisory published.
Version 1.0
Last Updated 2019-07-09
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