I have a little problem and I'm hopping that you can help me solve this annoying issue.
I need to use an iFrame in an administration panel to let users use the selection service, and in the HTML I have:
<iframe scrolling="yes" runat="server" title="Par Selection" id="iFrame"
frameborder="0" enableviewstate="true" width="100%" height="490" />
in my code-behind file I have:
iFrame.Attributes.Add("src", String.Format(
"https://www.parurval.se/urval/?username={0}&password={1}",
parSettings.GetSettings(parSettings.SettingsType.PARSelection, parSettings.SectionType.Username),
parSettings.GetSettings(parSettings.SettingsType.PARSelection, parSettings.SectionType.Password)));
The output is this:
<iframe id="tcMain_tabPARSelection_iFrame" scrolling="yes" title="Par Selection"
frameborder="0" width="100%" height="490"
src="https://www.parurval.se/urval/?username=myUsername&password=myPassword">
</iframe>
Please note the & instead & sign in the src address when passing username and password
How can I prevent this?
I tried with HttpUtility.Decode( myCompleteUrl ) but with the same achievement :(
The worst thing is, if the src code has only the address
... src="https://www.parurval.se/urval/" ...
I'm not able to input the user/pwd, I see the form and I can enter text, but it does nothing, it only refreshes the iframe inner page, doing this in a full window, works fine.
And in that administration panel I have a textbox to the user add the username and password in order that entering the Administration page, I will jump directly to the service in the iFrame so the user does not need to enter user/pwd to login every time, that is way I'm trying to add those values dynamically.
Any ideas?
Added:
If I put the correct URL address (with user and pwd) in the iFrame src attribute in the HTML side (not dynamically) all works fine :(
The presense of the & is actually correct there. Most browsers are forgiving enough not to choke on just seeing & there, but it's technically not correct.
“&” is a special character in HTML (more specifically in SGML), so encoding it is the correct thing to do. Yes, even in link URLs.
The HTML 4.01 specification states:
Authors should use "&" (ASCII decimal 38) instead of "&" to avoid confusion with the beginning of a character reference (entity reference open delimiter). Authors should also use "&" in attribute values since character references are allowed within CDATA attribute values.
So encoding the & as & is correct behavior since the interpretation of the src attribute value (CDATA data type) is described as:
CDATA is a sequence of characters from the document character set and may include character entities. User agents should interpret attribute values as follows:
Replace character entities with characters,
Ignore line feeds,
Replace each carriage return or tab with a single space.
Otherwise src attribute values like /foo?bar§=123 would be ambiguous as they can be interpreted either literally as /foo?bar§=123 or (replacing the sect entity) as /foo?bar§=123.
This seems like a case where you can take advantage of URL encoding to hide the &, bypassing XML encoding. & is U+0025, so you can encode it as %25: https://www.parurval.se/urval/?username={0}%25password={1}
You should use
HttpUtility.HtmlEncode(String.Format("https://www.parurval.se/urval/?username={0}&password={1}",
parSettings.GetSettings(parSettings.SettingsType.PARSelection, parSettings.SectionType.Username),
parSettings.GetSettings(parSettings.SettingsType.PARSelection, parSettings.SectionType.Password)));
Related
I have a seam component where I put a message using standard seam annotation:
#In
private StatusMessages statusMessages;
public void myMethod()
{
statusMessages.add("Welcome, #{user.getName()}, after confirmation you will be able to log in.");
}
and than in the xthml page to show this message:
<h:messages id="mensagensHome" globalOnly="true" styleClass="message"
errorClass="errormsg" infoClass="infomsg" warnClass="warnmsg"
rendered="#{showGlobalMessages != 'false'}" />
This is working perfectly, but I have a requirement where the name should be Bold. Than I have already tryed placing standard html tags in my message like:
statusMessages.add("Welcome, <b> #{user.getName()} </b>, after confirmation you will be able to log in.");
But than it shows the tags on the page and does not turn the name bold.
I have also tried using unicode escape character to render the html tags, but again no success.
Is it possible to use standard html tags from code looking forward to format messages in Seam?
Tx in advance.
Actually you can't, unlike h:outputText h:messages don't have an escape property where you would be able to do escape="false".
In the link bellow you can find a sample on how to extend h:messages, actually it's not exactly h:messages that is extended but the end result is the same. So you can set escape="false" in h:messages and have the browser parse html tags.
http://balusc.blogspot.com/2010/07/using-html-in-jsf-messages.html
Be careful if you display something that the user inserted because this is is prone to html injection.
Note: The link is not mine, but it did work for me.
In my markup I am using HTML title attributes which I set by the Tooltip property of various ASP.NET controls like an asp:Label. The content of those titles come from a database and I use data binding syntax, for instance:
<asp:Label ID="PersonLabel" runat="server"
Text='<%# HttpUtility.HtmlEncode(Eval("PersonShortName")) %>'
ToolTip='<%# HttpUtility.HtmlEncode(Eval("PersonFullName")) %>' />
Now, tooltips seem to be displayed as plain text on Windows and in the browsers I have tested. So the HTML-encoding is not what I really want and I am inclined to remove the encoding.
Can this be dangerous in any way if the database fields may contain script tags for example? My question is basically: Is it always guaranteed that HTML-title attributes are displayed as plain text? Are they always displayed as tooltips at all, or is it possible that some browsers (or OSs) display them in another way and allow and render HTML content in the title attributes?
Edit:
Looking at some of the answers it seems I didn't phrase my question well, so here are some additions:
If I have in the code snippet above a PersonShortName of "PM" in my database and as the PersonFullName a name with non-ASCII characters in it like Umlauts in "Peter Müller" the browser displays in the tooltip Peter Müller when I apply HttpUtility.HtmlEncode like in the code example - which is ugly.
I've also tested a simple HTML fragment like:
<span title="<script>alert('Evil script')</script>" >Hello</span>
The script in the title attribute didn't run in a browser with enabled Javascript (tested with Firefox), instead it was displayed in the tooltip as plain text. Therefore my guess was that title attributes are always rendered as plain text.
But as Felipe Alsacreations answered below there exist "rich tooltip plugins" which may render the title attribute as HTML. So in this case encoding is a good thing. But how can I know that?
Perhaps HttpUtility.HtmlEncode isn't the right solution and I have to filter only HTML tags but not encode simple special characters to make sure that the plain text is displayed correctly and to protect "rich HTML tooltips" at the same time. But it looks like a costly work - only for a simple tooltip.
Always sanitize output to the browser.
If a value like "><script>blabla</script> is inserted as a value for your fields, a user can essentially take over your entire site. It will probably make a mess when it comes to validation and correct code, but the script will still be run.
So to answer your question: No, it is not guaranteed that HTML-title attributes are displayed as plain text if the user knows what he/she is doing.
Beside security reasons:
Title attributes should always be plain text but certain JS plugins misuse them to display 'rich' tooltips (i.e. HTML code with bold text, emphasis, links and so on).
As for browsers and AFAIK they are displayed as plain text and tooltips, never displayed to those who use tabbed navigation (keyboard) and scren readers give to their users (blind and partially sighted people) many options, like reading the longest between link title and its text or always title or never ...
Surprisingly, still, no right answer in 5 years. The answer is: yes, you need to encode the title attribute, but not everything that is encoded in the innerText of the element.
The proper way to do it in asp.net if you do your own markup is:
string markup = string.Format("<div class='myClass' title='{0}'>{1}</div>",
System.Web.HttpUtility.HtmlAttributeEncode(myText),
System.Web.HttpUtility.HtmlEncode(myText));
The above will set both innerText and title of the div to myText, which is customary for elements that may contain long text but are constrained in width (as I believe the question implies).
The ToolTip property of a ASP.NET control will auto encode the value on output/rendering.
This means it is safe to set the tooltip to plain text as the page will sanitize the text on rendering.
Label1.ToolTip = "Some encoded text < Tag >"
Renders HTML output as:
<span title="Some encoded text < Tag >"></span>
If you need to use text that is already encoded, you can set the title attribute instead. The title attribute will not be automatically encoded on rendering:
Label1.Attributes("title") = "Some encoded text < Tag >"
Renders HTML output as:
<span title="Some encoded text < Tag >"></span>
Another point:
Who cares how the title attribute is rendered by a browser, when it is the presence of malicious strings in the source code that could present an issue?
It doesn't matter how it is displayed, the question is: how does it appear in the source code?
(As already stated, if you're pumping strings to the client, do something to sanitize those strings.)
I think there may be some confusion going on with this thread.
Firstly <asp:Label> is an ASP.NET Web Control. The Text and ToolTip attributes are "abstractions" of the inline content and 'title' attributes of an HTML tag respectively.
For these particular two properties Microsoft will perform the HTML Encoding for you automatically so if you set ToolTip="H&S<" then the <span> tag will be rendered as <span title="H&S<"...>. The same goes for the Text property.
NOTE: Not all properties perform automatic encoding (HTML or InnerContent properties for example)
If however you are generating HTML tags directly (Response.Write("<span...") for example) then you MUST http encode the text content and tooltip attributes content if:
Those values originate from a user / external unsanitised source or
If there is a possibility that the content may contain characters that should be escaped (& < > etc.)
Usually this means that it is safe to to:
Hardcoded content with no http characters:
Response.Write("<span title='Book Reference'>The art of zen</span>"); // SAFE
Hardcoded content with http characters that you manualle encode:
Response.Write("<span title='Book & Reference'>The art & zen</span>"); // SAFE
Dynamically sourced content:
Response.Write("<span title='"+sTitle+"'>"+sText+"</span>"); // UNSAFE
Response.Write("<span title='"+HttpUtility.HtmlEncode(sTitle)+"'>" +HttpUtility.HtmlEncode(sText)+"</span>"); // SAFE
I know it is be possible to do this:
<asp:Image runat="server" ImageUrl="~/MyImageHandler.ashx?imageid=2" />
...but I have a case where the byte array data is only available to the Page (ie, not available in the session, and cannot be referenced by an id) so I can't point the ImageUrl to a different page.
Is there a way of giving an asp:Image the byte array to render as an Image?
The major hurtle you're going to have to deal with is that an <asp:Image/> element gets rendered as a regular <img />, which needs a src attribute that points at a URL.
That being the case, I see two hairy alternatives:
Use the technique described here to embed your image encoded in Base64 in the src attribute. Note that this does not work with Internet Explorer.
Embed your Base64-encoded image into the page as a hidden <input /> element. You could then use JavaScript to POST that data back to the server, which would just send it back to the browser using Response.Write() (being sure to set the Content-Type appropriately, of course).
The only decent solution to this is to put the byte array in session. If you're concerned about uniqueness (multiple people getting each other's byte arrays), use a random GUID as the key.
I have an ASP.NET MVC application and I'm using CKEditor for text entry. I have turned off input validation so the HTML created from CKEditor can be passed into the controller action. I am then showing the entered HTML on a web page.
I only have certain buttons on CKEditor enabled, but obviously someone could send whatever text they want down. I want to be able to show the HTML on the page after the user has entered it. How can I validate the input, but still be able to show the few things that are enabled in the editor?
So basically I want to sanitize everything except for a few key things like bold, italics, lists and links. This needs to be done server side.
How about AntiXSS?
See my full answer here from similar question:
I have found that replacing the angel
brackets with encoded angel brackets
solves most problems
You could create a "whitelist" of sorts for the html tags you'd like to allow. You could start by HTML encoding the whole thing. Then, replace a series of "allowed" sequences, such as:
"<strong>" and "</strong>" back to "<strong>" and "</strong>"
"<em>" and "</em>" back to "<em>" and "</em>"
"<li>" and "</li>" back to ... etc. etc.
For things like the A tag, you could resort to a regular expression (since you'd want the href attribute to be allowed too). You would still want to be careful about XSS; someone else already recommended AntiXSS.
Sample Regexp to replace the A tags:
<a href="([^"]+)">
Then replace as
<a href="$1">
Good luck!
I am currently having troubles figuring out how to handle a filepath to be (dynamicly) passed out to a HyperLink control's NavigateUrl property.
Let's say that I'm trying to refer to a file named jäynä.txt at the root of C:.
Passing "file:///C:/jäynä.txt" result to a link to file:///C:/jäynä.txt, as does HttpUtility.UrlPathEncode("file:///C:/jäynä.txt").
Replacing the ä**s with **%E4, which gives the string "file:///C:/j%E4yn%E4.txt", does give a working link to file:///C:/jäynä.txt, but I have not been able to find a way to make the replacement without defining it myself. With Replace("ä", "%E4"), for example.
Is there a way to automaticly handle the filepath string so that the HyperLink would display it correctly, without manualy listing what characters to replace in the string?
Additional Note:
There may be a way to work around this by spesifying the character encoding in which the page is rendered, because debugging shows that the HyperLink at least saves the string "file:///C:/jäynä.txt" unchanged, but somehow mangles it around the time of rendering.
However, this seems only be the case in rendering of the NavigateUrl because other components as well as HyperLink's Text-property are all quite capable of rendering the character ä unchanged.
The NavigateUrl property of a Hyperlink will encode unicode chars in the url.
Instead you can set the href attribute property of the Hyperlink like this:
hyperlink1.Attribute("href") = "file:///C:/jäynä.txt"
This is due to how the browser starts to interpret the path, typically individuals will avoid using characters such as that in the urls of pages.
In your case, I believe you have struck upon the best case scenario, as I am not aware of any way to change the behavior of HttpUtility and/or the NavigateUrl property. At least not without creating a custom control for it.
Don't use HyperLink control. Instead use HtmlAnchor control. It will solve your problem. I don't know why Microsoft designed like this.
Thank you!
The post using the 'attributes' solved my problem. In my case it was
HyperLink6.Attributes["href"] = "http://høgstedt.danquah.dk/";
The problem of using special danish characters in a url seem to have been troubling a lot of programmers - a search provides several very complicated approaches. This one is SIMPLE and it SIMPLY WORKS.
So once again, thank you