alerting the user of "A potentially dangerous Request.Form value was detected from the client"

Question

I am getting this in ASP.NET 4 webforms. Now I know the user sends HTML in the textbox. my problem is that I want to alert him that he entered HTML and invalid content.

How can I do that?

Thanks

Answer 1

Setting validateRequest="false" will avoid this error, but it will leave the page vulnerable to a number of attacks which may be sql injection attacks also. Or use HTMLEncode on all fields where you are taking input.

For more detailed explanation have a look at following Stackoverflow question about handling suspicious content:

A potentially dangerous Request.Form value was detected from the client

Hope this helps.

Answer 2

I recomend to Parse the HTML Content entered by the user in your browser.