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Microsoft Security Advisory CVE-2019-0815: ASP.NET Core denial of service vulnerability #352
Microsoft Security Advisory CVE-2019-0815: ASP.NET Core denial of service vulnerability
Microsoft is releasing this security advisory to provide information about a vulnerability in public ASP.NET Core 2.2. This advisory also provides guidance on what developers can do to update their applications correctly.
Discussion for this issue can be found at aspnet/AspNetCore#9205
The vulnerability affects any Microsoft ASP.NET Core 2.2 applications if it is hosted on an IIS server running AspNetCoreModuleV2 (ANCM) prior to and including version 12.2.19024.2.
The vulnerability affects any Microsoft ASP.NET Core 1.0/1.1/2/1 application if they have explicitly opted into using the newer AspNetCoreModuleV2 (ANCM) prior to and including version 12.2.19024.2.
How do I know if I am affected?
You are affected if BOTH criteria below are met.
The modules attribute in the handler mapping section of the web.config of your application must exactly match the string
<?xml version="1.0" encoding="utf-8"?> <configuration> <location path="." inheritInChildApplications="false"> <system.webServer> <handlers> <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModuleV2" resourceType="Unspecified" /> </handlers> <aspNetCore processPath="dotnet" arguments=".\myapp.dll" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" hostingModel="inprocess" /> </system.webServer> </location> </configuration>
Open a PowerShell prompt and run the following command
(Get-Item "$env:ProgramFiles\IIS\Asp.Net Core Module\V2\aspnetcorev2.dll").VersionInfo
or use the Windows file properties dialog to check the version on C:\Program Files\IIS\Asp.Net Core Module\V2\aspnetcorev2.dll, where C: is your OS install drive.
How do I fix the issue?
Install the latest version of the ASP.NET Core Runtime & Hosting Bundle 2.2.
Then restart IIS by running
net stop was /y net start w3svc
from an elevated command line.
Reporting Security Issues
If you have found a potential security issue in .NET Core, please email details to firstname.lastname@example.org. 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.
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/. 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 where you can ask questions.
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.
V1.0 (Apr 9 2019): Advisory published.