Georgi Guninski security advisory #9, 2000

IE and Outlook 5.x allow executing arbitrary programs using .eml files

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There is a vulnerability in IE and Outlook 5.x for Win9x/WinNT (probably others) which allows executing arbitrary programs using .eml files.
This may be exploited when browsing web pages or openining an email message in Outlook.
This may lead to taking control over user's computer.
It is also possible to read and send local files.

The problem is creating files in the TEMP directory with known name and arbitrary content.
One may place a .chm file in the TEMP directory which contains the "shortcut" command and when the .chm file is opened with the showHelp() method programs may be executed.
This vulnerability may be exploited by HTML email message in Outlook.

The code that must be included in a .eml file is:
<IFRAME align=3Dbaseline alt=3D"" =
border=3D0 hspace=3D0=20
Content-Type: application/binary;
Content-Transfer-Encoding: base64
Content-ID: <000701bf8458$eb570380$dc0732d4@bbb>

...Put the base64 encoded .chm file here...

Demonstration which starts Wordpad: eml.html

Workaround: Disable Active Scripting.

Copyright 2000 Georgi Guninski

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