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