Web Forms :: HttpRequestValidationException - Handling Cross Site Scripting (XSS)?
Oct 25, 2010
this exception is caused by entering scripts or disallowed text as "<script>", "<h1>" by the user. This exception will be thrown while processing the request.
After searching and trying, most of the solutions were to:
1- disable request validation in the page header (validateRequest="false") or in the pages section in web.config.
I dont see this is a solution, the XSS problem is still there, it just does not throw the exception.
2- To encode the text and decode it using Server.HtmlEncode and Server.HtmlDecode.
This is a good one, but have to go every single textbox and call this method (Server.Encode(txtAddress.Text)), but this require alot of effort to change the whole site, and some of them may be forgotten.
I was thinking of creating a new TextBox control (MyTextBox) to inherit from System.Web.UI.WebControls.TextBox and override the Text property, then Encode base.Text in the get accessor, and Decode base.Text in the set accessor.
This will also require to change the whole site, to use MyTextBox instead of TextBox.
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Jan 21, 2010
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Mar 25, 2010
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[Code]....
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Mar 9, 2011
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May 14, 2010
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Jul 30, 2010
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Jan 16, 2010
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Nov 16, 2010
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Mar 16, 2010
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Jun 15, 2010
I am using asp.net 3.5 and have validateRequest="true" in the machine.config.
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Nov 29, 2010
Like many others, my web site now throws the following exception under .NET 4.0 where it used to behave perfectly well under .NET 2.0:
A potentially dangerous Request.Form value was detected from the client.I have added the following element to my web.config file:
<httpRuntime requestValidationMode="2.0" />
However, the error still appears. It is caused by the log-in and log-out buttons on my site, which are contained in a master-page. I think the reason might be because I make extensive use of hidden fields in my web pages, which the ASP.NET validation now complains about when the pages are posted back to the server after the buttons are pressed:
A potentially dangerous Request.Form value was detected from the client (ctl00$ctl00$mainContent_PH$mainContent_lCol_PH$hdnPageContent="...ssociation's Executive Com...").
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Feb 17, 2011
I have this piece of code to handle the HttpRequestValidationException in my global.asax.cs file.protected void Application_Error(object sender, EventArgs e)
[code]...
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Mar 18, 2011
Is there a way I can handle HttpRequestValidationException without turning off ValidateInput?
What I really want is all HTML posted from a form to be automatically encoded in the model unless a particular property has the AllowHtml attribute set.
If I have to turn off ValidateInput, then what happens to the rest of my model validation? Will it still be validated or do I need to explicitally check ModelState.IsValid?
I'm also catching the exception in a custom model binder class but every time I try to access the offending property from Request.Form, the exception gets thrown. Is there a way to get that value in the model binder?
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Nov 12, 2010
I think I might have stumbled onto a bug in ASP.NET MVC 3 RC. When I setup my MVC2 project in a new MVC3 project, copy paste classes, code, change name spaces, etc, etc, I ran into an issue in the following, simplified for explanation purpose, scenario:
Model:
public class WineDetails
{
[SkipRequestValidation]
[Required(ErrorMessage = "Beschrijving verplicht")]
public string Description { get; set; }
}
ViewModel:
public class ViewModelCreateWine
{
public MasterData MasterData { get; set; }
public WineDetails WineDetails { get; set; }
}
ActionMethod:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult CreateWine(ViewModelCreateWine viewModelCreateWine)
{
GetMasterDataRegions(viewModelCreateWine);
if (Request.Params.ToString().IndexOf("Save") > 0)
{
if (TryValidateModel(viewModelCreateWine.WineDetails))
{
m_wineService.CreateWine(viewModelCreateWine.WineDetails);
return RedirectToAction("index", "Admin");
}
}
return View(viewModelCreateWine);
}
The ActionMethod "CreateWine" needs to call the "CreateWine" method in the WineService so that in the end a new Wine is added to the Database. So far it looks ok. As shown in the above code the [SkipRequestValidation] is set on the "Description" property of the WineDetails model so that the user can add Rich Text to the description and HTML elements are allowed during the Request validation. This works perfectly fine until the Params collection of the Request is accessed in the code to check if the Save button is clicked. When this line of code is trying to execute the following exception is thrown:
Exception Details: System.Web.HttpRequestValidationException: A potentially dangerous Request.Form value was detected from the client (ViewModelCreateWine.WineDetails.Description="<p>HTML Content with...").
The same exception is thrown when I put the [ValidateInput(false)] attribute on the action method. When I comment out the "if" statement and its content there is no issue and the model validation works just fine and skips the Request Validation on the Description property as expected.
In MVC2 the above code worked fine with the [ValidateInput(false)] attribute on the action method.As I said I'm not sure if this is a bug, it very well might be my own stupidity, but I thought it would be worth to mention here. So any feedback is more than welcome.
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Feb 10, 2011
In the load event of a web user control I have the following code which I am using to call a function in order to populate a HTML Text Area.The page hosting the control loads fine the first time it loads but on postback it throws the error
Quote:System.Web.HttpRequestValidationException: A potentially dangerous Request.Form value was detected from the client
I have seen people suggest <%@ Page ... validateRequest="false" %>
Firstly I would like to handle this at control level rather than on the hosting page .
Code:
if (!Page.ClientScript.IsStartupScriptRegistered("AddText"))
{
Page.ClientScript.RegisterStartupScript [code]....
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Aug 17, 2010
I'm setting up a fairly complex gridview, and running into an issue with allowing some keyboard shortcuts to cause a submission postback. I'm hooking the onkeydown event on all of the editable elements within my gridview (in edit mode, as well as a separate-but-similar set of elements in the footer, used for row insertion), and calling the following function:
[Code]....
Here is the definition of LinkButton1, which is within a TemplateField in MasterGridView:
[Code]....
The gridview is not populated until after the user has made some input to the page, so I can't just refer directly to MasterGridView.SelectedRow.FindControl("LinkButton1").UniqueID for my eventTarget within the PostBackOptions (if I run this right now, it'll evaluate to "not initialized". But, I don't know how I could get it to recheck the value after the page has been created. There's gotta be a better way to make this work.
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Jan 24, 2016
Please click <a onclick="self.close();" href="#">here</a> to close this window. this is my code .
when i submit in chrome and mozilla it shows the error.
" script must not be allowed to close a window that was not opened by that same script."
I tried with
function quitBox(cmd) {
if (cmd=='quit') {
open(location, '_self').close();
}
return false;
}
but it does not work for me
window.open('', '_parent', '');
window.close();
and also with this script.
how i close the tab on clicking the close tab.
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Jul 21, 2010
I've seen the <script type="text/C#> with intellisense.
If it is possible to script client side scripts in C#, some infomation or reference on how to do it. For example, do I need using statements, is the script compiled on the server.. etc.
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Oct 6, 2010
I am getting my database copies as sql script every week. I want the copies as it is on the server.
but there are a lot of option on the scripting. which ones do I need to choose for a proper copy.
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Oct 28, 2010
I have a site created using .net and the ajaxcontroltoolkit. When some users log on they do not see the controls on the page. I can duplicate this if I disable active scripting in ie. The problem is that the users I have spoken with have active scripting enabled. I have had them navigate to a site that tests javascript and it passes. Has anyone experienced this problem? If so what was your solution?
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May 20, 2010
The programmer is a C# ASp.NET Developer and is looking to learn his first scripting language. Unfortunately he never had to use it before. He is also looking for something that can be good for his career growth.
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