<clear> Element for schemeSettings (Uri Settings)
Clears all existing scheme settings.
<configuration>
<uri>
<schemeSettings>
<clear>
Syntax
<clear/>
Attributes and Elements
The following sections describe attributes, child elements, and parent elements.
Attributes
None.
Child Elements
None.
Parent Elements
| Element | Description |
|---|---|
| <schemeSettings> Element (Uri Settings) | Specifies how a Uri will be parsed for specific schemes. |
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 that clears all scheme settings and then adds support for not escaping percent-encoded path delimiters for the http scheme.
<configuration>
<uri>
<schemeSettings>
<clear/>
<add name="http" genericUriParserOptions="DontUnescapePathDotsAndSlashes"/>
</schemeSettings>
</uri>
</configuration>
