Given a simple text box in the form:
<input type="text" … >
Is there any way for the user to inject a line break?
I know that it is possible to fake a form using curl or other technology, so I’m not relying on this as a form of protection. It’s more a question on whether a user can do this simply.
Thanks
No, they can't enter a new line in a text input.
They can, however, replace the input with a textarea in their browser's DOM inspector or bypass the form entirely and send an HTTP request with whatever data they want in it.
Related
I have a form with a text field that users input text into. They can use multiple lines, put in bold text, underlined text, etc., but the text, when saved to SQL Server doesn't have any formatting saved, just the text is saved. What is the best way to save the text with the HTML so that when it gets viewed by another user and pulled up from Sql Server the HTML is saved and the formatting is saved?
Ex.
hello
Paul
This would be saved as
helloPaul
you can't see it but there are bold and carriage return html tags rapped around the text
When receiving data from the user, on the server side code, use HTML encode to safely store the data:
var inputData = Server.HtmlEncode("<strong>some data input from user</strong>"); //insert your user input data variable here
Then when displaying the data in your cshtml page, decode the data to display it as the user entered it:
HttpUtility.HtmlDecode(saveUserDataFromDatabaseVariable);
All this is assuming you have a rich text editor being plugged into the input field. CKEditor and TinyMCE are good ones.
You can use a text editor. Take a look at CKEditor. It's free and easy to use :)
Can you post some code and more details?
I have had good success with CKEditor. It is customizable, and its content can easily be saved via postback to a standard asp:TextBox.
It is possible that the editor you are using is not actually updating the input/textarea that you are using, it may be cloning the text and drawing the formatting in an overlay. You can use developer tools, or javascript, to verify this by checking the value property of the input or textarea element. If it is being saved via AJAX or javascript the code may be using the textContent or innerText properties instead of innerHTML.
I used the richtexteditor dll that's free online. it gave me a wiziwig box that the user can edit texxt in.
I am trying to retain the users inputs in a textarea on my ASP classic form, so that if the recaptcha is entered wrong then the user's input is not lost and they only have to re-enter the captcha text. I am able to retain the input from a normal text box using value="<%=session("Address")%>". But the same thing does not work for textareas. I have seen a solution for PHP and so was hoping there was something available for ASP. How can i go about doing this, and if possible I would prefer to keep it server side? Thanks in advance.
like so:
<textarea name="" id=""><%=session("Address")%></textarea>
Keep in mind that you should not put out user generated texts directly in your site. think of malicious JavaScript code in session("address")...
you should encode those values like so:
<textarea name="" id=""><%=server.htmlencode(session("Address"))%></textarea>
same for all other places where you "inject" user generated values in your site...
I am able to write value to an input t form type= text
for ex
<input type="text" value="xyz">
But what i want is, to write a value to input type="file" . I have tried the code below but it's not working.
<input type="file" value="something">
You cannot, for fairly obvious security reasons.
If a webpage could specify a default value for a file input, then it could (for example) specify c:\place\where\finance\software\stores\accounts\by\default (and then use JavaScript to submit the form without the user having to do anything).
PHP aside, HTML doesn't let you assign values to input type="file" elements as a security measure. If HTML had this power, you could setup several of these fields and point each one to a windows file on the user's computer. The result would be a victim submitting a form with no idea they were also submitting sensitive information. No JavaScript is required. The victim might submit such a form to log in or post a comment on a blog somewhere. Why wouldn't the victim notice they are also submitting a file? CSS can style such elements offscreen using negative coordinates so its a lot like an input type="hidden", just in this case it would submitting a file instead.
I was wondering whether it is possible to assign a value to an HTML text box and protect it.
What I mean is make it´s content unmodifiable, so that when the form gets submitted im "sure" it was this value which was submitted.
BTW I realize the easier way would be not to "listen" fot this input and just assign it but it would come in handy to be able to do what´s stated above.
I hope the question is clear enough, please ask for any needed clarification.
Thanks in advance!
EDIT: I was definitely not clear enough but I tried to express that i should hold the value after submitted (not modifiable in client side)
No, it's not. You should never trust user input, which includes form submissions.
The other answers tell you how to mark the field as read-only. This is useful if you want to display a particular value, while showing that it's not intended to edited.
However, it can still be modified with Firebug, DOM Inspector, etc. Or, they can just submit a HTTP request without using the browser at all.
I would recommend storing the value in a session instead.
Set the readonly property of the input element:
<input type="text" readonly="readonly" />
This will prevent any modification (except if the user edits with a DOM Inspector). Always validate input on the server. If you do not want any changes made, don't allow the user to edit it.
http://www.w3schools.com/tags/att_input_readonly.asp
Form inputs have a 'disabled' and 'readonly' attributes you can set to make them un-editable.
http://htmlhelp.com/reference/html40/forms/input.html
Though you can never be 100% sure what is getting sent from the client side. The entire DOM is editable by the client.
Just do this
<input type="text" value="VALUE" readonly />
Then itll be read only :)
<input type="text" readonly="readonly"/>. But: Never be sure, and validate data on the server side. It is very easy to request GET/POST with invalid data.
I have a web page with a read-only text box which shows some HTML code:
<input type="text" readonly="true" value="<table>...</table>"/>
There is also submit button, which causes page post back and XSS validation to trigger. I don't want to turn off XSS.
I also tried disabled="disabled", but then the user is not able to copy the text in the text box.
So I thought that using div and span which can give same look and feel would suffice and negate the need for turning off the validation. While trying this, I am struggling to restrict the string in one line. As in text box, it is a single row with column size and text is shown nicely, we can also copy text.
Is there a better solution for what I'm trying to do?
If I understand you correctly you're trying to show some example code in a web interface that is formatted for easy consumption by the end user.
As a general rule, you should wrap code snippets in <pre></pre> tags, I would then suggest having a go at using: http://alexgorbatchev.com/wiki/SyntaxHighlighter to format the code as if you were viewing in an IDE.
This will prevent you from having to turn of the XSS checker.
you could use <pre> tags
check this link