a potentially dangerous requestquerystring value was detected from the client - Templates, (partial) views and macros

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Ritesh 11 posts 91 karma points

Apr 04, 2017 @ 10:59
0

A potentially dangerous Request.QueryString value was detected from the client.
Hi,

I have a search functionality where I want to secure user inputs.
```
<form action="@urlToSearch" id="searchform" method="get">
    <div>
          <input type="text" id="s" name="s" value="@searchText" placeholder='Search' />
          <input type="submit" value="" id="searchsubmit" class="button avia-font-entypo-fontello" />
    </div>
</form>
```
While unit testing, I have entered "
```
<script>alert('hello');</script>
```
" and the page goes to "A potentially dangerous Request.QueryString value was detected from the client (s="script>alert('hello...")."

When searching keyword home, url looks like http://localhost/search/?s=home

Can anyone guide me on this, how can I secure my page from malicious attacks?

Already tried adding <httpRuntime requestValidationMode="2.0"> into web.config

Using Umbraco 7.5.11 assembly: 1.0.6274.27352

Thanks in advance.
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Michael Latouche 504 posts 819 karma points MVP 4x c-trib

Apr 04, 2017 @ 14:47

0

Hi Ritesh,

From what I read, it seems your page is secured already since it returned an error when you tried to enter malicious input data.

Or do you want to have the possibility to actually search on such "malicious words"?

Cheers,

Michael.

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Ritesh 11 posts 91 karma points

Apr 05, 2017 @ 11:02

0

Thanks Michael for your reply. I am looking for similar scenarios and how that can be handled? e.g. showing some custom message or disallow users to enter such text input.

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Michael Latouche 504 posts 819 karma points MVP 4x c-trib

Apr 05, 2017 @ 11:26
100
Hi Ritesh,

Here are a few ideas that come to my mind:
- client side validation via RegEx of some kind, so you can then show a custom warning text and prevent form submission
- Catch the exception in you global.asax Application_Error method. If you implement a "unhandled exceptions Handler" in your global.asax file, as described here, you will actually get in there with an exception of type
```
System.Web.HttpRequestValidationException
```
So you can make a check on the exception type, and if you get that specific type, you can display your custom message, redirect to a specific error page, etc.
- remove the built-in validation from your config file and do the validation yourself at the server side. This allows you to handle this anyway you want, but you have to make sure that your validation rules are bullet-proof ;-) And never forget to use "Html Encoding" when displaying the data.
Hope this helps.

Cheers,

Michaël.
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Vikas 3 posts 73 karma points

May 07, 2021 @ 11:36
0
Old question, but if anyone stumbles upon this, you can use below code in web config to entirely removing validation for specific folders files
```
 <location path="YourFolder/.aspx">
<system.web>
  <pages validateRequest="false" />
  <httpRuntime requestValidationMode="2.0" />
</system.web>
```
Source: https://qawithexperts.com/questions/303/a-potentially-dangerous-requestform-value-was-detected-from Hope it helps.
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A potentially dangerous Request.QueryString value was detected from the client.