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Excel Users Open To New Attack
A new type of attack has been identified allowing a malicious
user to perform any actions the user could.
By: Victor Latona, Updates.com Wednesday July 26, 2000 12:00
AM
Redmond, WA. Microsoft Corporation has released an update
for its popular spreadsheet program. Versions of Microsoft
Excel are vulnerable to an exploit that could allow malicious
code to run on a user's computer without notification. \A
recently revealed vulnerability in Microsoft Excel 2000 and
Excel 97 identified a method of executing code on a user's
computer without their permission or knowing. According to
Microsoft, "The code executed on the affected user's computer
can perform any action the user could perform on the machine."
This includes deleting every file on your hard drive. The
two versions of Microsoft Excel have a REGISTER.ID function
that can be misused to run malicious code. The REGISTER.ID
function was intended to return the register ID of a DLL (dynamic
link library) or code resource that has been previously registered
and it is a normal worksheet function. However, due to a Microsoft
error the REGISTER.ID worksheet function allows a DLL to be
referenced from a worksheet without warning to user. For the
attack to be successful the malicious user would need to produce
a damaging DLL and have it referenced from an Excel worksheet
using the REGISTER.ID function. Also, the DLL would need to
reside on the users computer or a network share. Windows 2000
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If the attacker meets the two above-mentioned conditions the
payload of the damaging DLL can be unleashed when the user
opens the Excel document. With this exploit the user is not
given the opportunity to choose whether they would like to
open the document, as is given when a macro is enabled in
a workbook. This is how code can be run without the user knowing
it. The fix supplied by Microsoft disables the REGISTER.ID
function from both Excel 2000 and Excel 97. It is recommended
that all users of the affected versions download the patch.
Download
REGISTER.ID security update for Excel.
Note: To use the REGISTER.ID security update, Excel 2000 users
must have installed Office 2000 SR-1 or SR-1a.
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