4th Feb 2003 [SBWID-5967]
COMMAND
Internet Explorer local file reading
SYSTEMS AFFECTED
ie 6 sp1 + all patches
PROBLEM
jelmer [[email protected]] found :
We already knew pressing the back button on IE is dangerous
http://online.securityfocus.com/archive/1/267561
So it wont come as a total shock that so is clicking a link :) The
problem lies in the dragdrop method that was added as a method on
nearly all HTML elements in ie5.5 This method makes any element act
like its being dragged.
It is possible to abuse this behaviour to drop text in a html upload
control thus allowing you to read any file from an unsuspecting users
harddisk. In order for it to be succesfull the name of the file must be
known
basicly drag and dropping text takes a couple of steps
- select text
- press mouse
- move mouse over over an element that can accept it
- release mouse.
It is possible to mimic all the above steps but the pressing of the
button by using javascript
a demo is provided at
http://kuperus.xs4all.nl/security/ie/xfiles.htm
it isn't very elegant but seems to work most of the time (ie acts a
little flakey at times), there are probably better ways to do it if you
know of any let me know ;)
references:
http://webreference.com/programming/javascript/dragdropie/3.html
http://msdn.microsoft.com/workshop/author/dhtml/reference/methods/dragdrop.asp
- Also -
Andreas Sandblad
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adds :
This is not the first time we have seen user interaction problems with
the upload control. Maybe you remember: "Pressing CTRL in IE is
dangerous"
http://online.securityfocus.com/archive/1/283866
(Taking advantage of pasting. SHIFT also works because SHIFT-INSERT =CTRL-V)
Btw, we only need to know the relative path. For example we can use:
"..\\Cookies\\index.dat"
instead of
"c:\\jelmer.txt"
SOLUTION
None yet