<schemeSettings> Element (Uri Settings)

Article
09/15/2021

Specifies how a Uri will be parsed for specific schemes.

<configuration>
<uri>
<schemeSettings>

Syntax

<schemeSettings>
</schemeSettings>

Attributes and Elements

The following sections describe attributes, child elements, and parent elements.

Attributes

None

Child Elements

Element	Description
add	Adds a scheme setting for a scheme name.
clear	Clears all existing scheme settings.
remove	Removes a scheme setting for a scheme name.

Parent Elements

Element	Description
uri	Contains settings that specify how the .NET Framework handles web addresses expressed using uniform resource identifiers (URIs).

Remarks

By default, the System.Uri class un-escapes percent encoded path delimiters before executing path compression. This was implemented as a security mechanism against attacks like the following:

http://www.contoso.com/..%2F..%2F/Windows/System32/cmd.exe?/c+dir+c:\

If this URI gets passed down to modules not handling percent encoded characters correctly, it could result in the following command being executed by the server:

c:\Windows\System32\cmd.exe /c dir c:\

For this reason, System.Uri class first un-escapes path delimiters and then applies path compression. The result of passing the malicious URL above to System.Uri class constructor results in the following URI:

http://www.microsoft.com/Windows/System32/cmd.exe?/c+dir+c:\

This default behavior can be modified to not un-escape percent encoded path delimiters using the schemeSettings configuration option for a specific scheme.

Configuration Files

This element can be used in the application configuration file or the machine configuration file (Machine.config).

Example

The following example shows a configuration used by the Uri class to support not escaping percent-encoded path delimiters for the http scheme.

<configuration>  
  <uri>  
    <schemeSettings>  
      <add name="http" genericUriParserOptions="DontUnescapePathDotsAndSlashes"/>  
    </schemeSettings>  
  </uri>  
</configuration>

Element Information

Namespace: System

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