ASP.NET Request Validation

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ASP.NET Provides built-in request validation on form submission or postback handling. Request validation is on by default, and is handled differently by versions of the framework.

Contents

ASP.NET 1.1 Request Validation Summary

  • Filter "&#"
  • Filter ‘<’ then alphas or ! or / (tags)
  • Filter "script:"
  • Filter on handlers (onXXX=)
  • Filter “expression(“
  • Ignore elements named "__VIEWSTATE"


ASP.NET 2.0 Request Validation Summary

  • Filter "&#"
  • Filter ‘<’ then alphas or ! or / (tags)
  • Ignore elements with names prefixed with double underscore (__)


To toggle request validation (it is set to true by default):

On a single page:

 <%@ Page validateRequest="true|false" %>

For the entire application:

 <configuration>
    <system.web>
         <pages validateRequest="true|false" />
    </system.web>
 </configuration>

References

Validation - Preventing Script Attacks
ASP.NET 2.0 dumb’s down request validation (by Michael Eddington)