I need to allow the user to submit queries as follows;
/search/"my search string"
but it's failing because of request validation, as outlined in the following 2 questions:
How to include quote characters as a route parameter? Getting "Illegal characters in path" message
How to modify request validation?
I'm currently trying to figure out how to disable request validation for the quote character, but i'd like to know the risks before I actually put the site live with this disabled? I will not disable the request validation unless I can only disable it for the quote character, so I do intend to disallow every other character that's currently not allowed.
According to the URI generic syntax specification (RFC 2396), the double-quote character is explicitly excluded and must be escaped (i.e. %22). See section 2.4.3. The reason given in the spec:
The angle-bracket "<" and ">" and double-quote (") characters are excluded because they are often used as the delimiters around URI in text documents and protocol fields.
You can see easily why this is the case -- imagine trying to create a link in HTML to your URL:
<a href="http://somesite/search/"my search string""/>
That would fail HTML parsing (and also breaks SO's syntax highlighting). You also would have trouble doing basic things with the URL like emailing it to someone (the email client wouldn't parse the URL correctly), posting it on a message board, sending it in an instant message, etc.
For what it's worth, spaces are also explicitly excluded (same section of the RFC explains why).
Related
For example, if for whatever stupid reason I configured my server to parse the URL by splitting the queries by the "^" symbol (escaped if necessary) and the "-" symbol instead of the "?" and "&", would I run into any trouble at all apart from a confused user?
Will the browser/HTTP request sent treat it differently in a way that may be detrimental to my up and coming "power minus" business?
? is not arbitrary but defined in the URI RFC section 3.4 Query, I dont' think you can change that.
The Query component internal syntax (how name=value couples are encoded) is not defined by the URI RFC, separators can be defined by other specifications:
& is defined as separator of the application/x-www-form-urlencoded content type by HTML Spec. You may change this aspect supporting for example ; as separator, but you would have in any case to support & for when processing the request produced by an HTML FORM.
I have a web application that places the user's search term in the query string, in a similar way to Google. E.g. the address might be www.example.com/mysearchpage.aspx?q=searchTerm.
Usually this works fine, but if there is a special character in the search term such as â, the action attribute on the form is encoded to percent encoding and the character is replaced with %u00e2.
If I search for chât I will end up with the URL www.example.com/mysearchpage.aspx?q=châtin the browser's address bar but the action attribute on the form that comes back from the server would be www.example.com/mysearchpage.aspx?q=ch%u00e2t which means that a subsequent form submission fails because the URL is incorrectly formatted.
I have ensured that in IIS the encoding is set to be UTF-8 for Requests, Response Headers and Responses. I have also inspected the page being delivered from IIS in Fiddler and that already includes the incorrectly encoded action.
The encoded format appears to be in a non-standard format as explained in this wikipedia article.
Is there a way to prevent IIS from encoding the form's action in this way?
The solution was to add targetFramework=4.5.2 into the httpRuntime tag in the web.config file.
Previously this was not specified but was specified in the compilation tag, however specifying targetFramework=4.5.1 still caused the problem.
I am using the RegEx "^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*#[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+[.])*(\.[a-zA-Z]{2,17})$"to validate Email but my lead want to validate as per the Microsoft standard. SO i need to follow
http://msdn.microsoft.com/en-us/library/01escwtf(v=vs.100).aspx
In that everything working fine as per the standard but still i am facing the issues with
Valid: js#internal#proseware.com
Valid: j_9#[129.126.118.1]
the above mentioned mail ID is still returning as invalid. I tried using the regex used in that page
^(?("")(""[^""]+?""#)|(([0-9a-z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-z])#))(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-z][-\w]*[0-9a-z]*\.)+[a-z0-9]{2,17}))$
but i am getting the error in the server page. Though I pasted the expression inside the validation Expression it can't able to accept the characters.
Note : am using ASP.Net validators for validating the email.
Description
To match both of those email addresses in your sample text, I think I would rewrite your expression like this:
[A-Z0-9._%#+-]+#(?:[A-Z0-9.-]+\.[A-Z]{2,4}|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\])
If you're looking to use this to validate a string which may contain only an email then you can add the start/end of string anchors ^ and $.
Example
Live Demo
Sample Text
Valid: js#internal#proseware.com Valid: j_9#[129.126.118.1]
Matches
[0][0] = js#internal#proseware.com
[1][0] = j_9#[129.126.118.1]
I'm pentesting the ASP.NET application running on Microsoft-IIS/7.5 web server and I'm sending it the following GET request parameters:
&search=aaa%20%*+,-/;<=>^|"'bbb
One of the parameters is search, where I've inputed the value that can be seen above. The value is printed in the returned response two times as follows:
The first parameter:
<input name="nn" type="text" value="aaa %* ,-/;<=>^|"'bbb" class="cc" />
Quoted parameters in the first entry are as follows:
" ==> "
' ==> '
< ==> <
I guess there's no way to break out of there, since the value is escaped and we can't input the " character right. Nevertheless, all parameters are not properly escaped, even though it's not possible to break out.
The second parameter:
<strong>aaa %* ,-/;<=>^|"'bbb</strong>
We can see that all of the characters are presented as they are, but there's a catch. After the < character there can't be any [a-zA-Z0-9] (maybe some other as well) characters, because we're probably getting blocked by the ASP.NET filters.
If we input the following:
&searchQuery=aaa<#script>alert('Hi');<#/script>bbb
We get the following output:
<strong>aaa<#script>alert('Hi');<#/script>bbb</strong>
I'm asking if you see any way to break out of the restrictions and execute arbitrary JavaScript code nevertheless?
THank you
HTML requires the tag name to immediately follow the start tag open delimiter <:
Start tags must have the following format:
The first character of a start tag must be a U+003C LESS-THAN SIGN character (<).
The next few characters of a start tag must be the element's tag name.
[…]
Anything beyond that is up to a browser’s interpretation quirks.
But there are also other tags than element tags like markup declaration tags (<!…>), processing instruction tags (<?…>) and alternative comment tags (<%…%>) that are recognized by certain browsers and allow certain hacks.
Have a look at the common XSS cheat sheets like OWASP’s XSS Filter Evasion Cheat Sheet and the HTML5 Security Cheatsheet, or some HTML fuzzers like Shazzer.
In some javascript, I have:
var url = "find.aspx?" + "location=" + encodeURIComponent( address );
alert( url );
location.href = url;
where the value of address is the string "Seattle, WA".
In the alert I see
find.aspx?Seattle%2C%20WA
as I expect.
But on the server side, when I look at Request.Url, the relevant substring I see is
find.aspx?Seattle, WA
And in the Firefox url window I see
find.aspx?location=Seattle%2C WA
So I'm getting three different representations whereas I would expect that in all three places I should see what I see in the alert. My expectation is that the url I assign to location.href should show up as-is in the browser url window, and should be passed as-is to the server in Request.Url (and I would need to decode the values on the server before using them). What's happening?
Firefox converts certain encoded characters into their literal forms as a way to be friendly to users. It will also convert spaces typed into the address bar into %20 for the server.
Update: The reason Firefox doesn't display the comma unencoded is because commas are allowed in URLs, but spaces are not, so it knows that a space is going to be unambiguously interpreted, whereas the pre-encoded comma is different from a non-encoded comma to some servers. see: Can I use commas in a URL?
ASP is probably trying to help you out by auto-un-encoding the string for you.
Update: It looks like ASP.NET unencodes Request.Url for you by default, as mentioned here: QueryString malformed after URLDecode They also mention that you can use HttpRequest.Url.Query to access the un-decoded version.
The alert is the only thing not doing any "magic" for you.
For the alert, you are doing the encoding yourself. Perhaps it looks the same as on the server-side if you removed encodeURIComponent.
On the server side, ASP.NET will always show you the unencoded form. This is to make it easier to directly map to files that also have text that needed to be (un)encoded.
Note that you can replace every letter for its UTF8 representation in URL Encoding. It will still be the same URL. I.e., type the following in the browser window and it will still work: %66%59%6E%64.aspx?location=Seattle%2C%20WA. To only encode the necessary chars, use UrlEncode on the server side if you create a link yourself.
URL encoding can become fairly tricky. You ask to explain it. To know the correct escape of a certain character, you need to know how that character looks in UTF8. The hexadecimal value of the UTF-8 bytes then become the %XX%YY value of your letter. Sometimes it's one %XX, but it can be up to six byte sequences in total (some Chinese characters for instance).
URL Encoding works one way only. Never double-encode or double-unencode. This is prohibited by the specification. Also, because you can encode any character, it is not always possible (as you found out) to do roundtrip encoding/unencoding. If you unencode and re-encode again, it is well possible that the resulting string is different, but syntactically the same.
In HTML, URL Encoding is sometimes interspersed with HTML Encoding. I.e., the ampersand is valid in HTML, but not in HTML. find.aspx?city=A&name=B becomes find.aspx?city=A&name=B in and HTML URL. However, browsers are lenient and will accept wrongly HTML-encoded strings.
Finally, a not on the browser: if you type in a space in a link, even inside an <a> tag, it will escape the space (or other character) for you. Likewise, it will nowadays show the odd characters (é, ï etc) in the address bar, but when it sends it over HTTP, the browser will correctly do the encoding for you.
Update: about anwering your question of needing a "definitive" reference or proof.
While I couldn't find any on the internet, I decided to look for it myself using Reflector. Going through the methods that set, for instance, the HttpRequest.QueryString, you quickly encounter the private method HttpRequest.FillInQueryStringCollection which then calls HttpValueCollection.FillfromEncodedBytes. Somewhat near the end of that method, HttpUtility.UrlDecode is called for the values. Conclusion: do not call it yourself, to prevent double decoding.
You can see this for yourself when you download Reflector and disassemble the .NET libs of System.Web.
For your example you can change this line
var url = "find.aspx?" + "location=" + encodeURIComponent( address );
to
var url = "find.aspx?" + "location=" + address;
and see the address as it is. Bu if address variable contains any '&' character your variable will be corrupt. So you are using encodeURIComponent to encode these things url.
On the Server side all these encoded strings are decoded back. It means encodeURIComponent is just for sending the address variable (whether it contains & character or not) to server side correctly.