Last revised: Mon Oct 15 09:32:36 EDT 2001
Source: CERT/CC
A complete revision history can be found at the end of this file.
According to Microsoft, versions of Excel and PowerPoint (or indeed, other products in the
Office suite) prior to this may be affected, but may be outside of
hotfix support. [For example, Symantec
states that Microsoft Excel 97 and Microsoft Powerpoint 97 are
vulnerable.] Because Microsoft Excel 97 and Microsoft Powerpoint 97 are
outside of the hotfix support window, these products may be
vulnerable, but not eligible for a hotfix. For more information
regarding hotfix eligibility status, please see the Microsoft
Product Support Services webpage. In general,
Microsoft no longer tests software outside of hotfix status for vulnerabilities,
and does not provide patches to address vulnerabilities that may be
discovered in that software.
Quoting from Microsoft Security Bulletin MS01-050
It's important to understand that Excel and PowerPoint 97 do
not have the same macro security framework as Excel and PowerPoint
2000 and 2002. The Excel and PowerPoint 97 macro security framework
lacks many key features that the 2000 and 2002 macro security
framework has, including a digital signature trust model that allows
trusted, signed macros to be differentiated from untrusted, unsigned
macros. Under this older framework, it is difficult for a user to make
an informed decision regarding the trustworthiness of macros. In
addition, as noted under "Tested Versions", Excel and PowerPoint 97
are no longer supported products. Because of these two issues,
customers who are concerned about macro security are urged to upgrade
to a support version with a more robust macro security model.
Systems Affected
Systems running:
Overview
An intruder can include a specially crafted macro in a Microsoft Excel or PowerPoint document that can avoid detection and run automatically regardless of the security settings specified by the user.
I. Description
Microsoft Excel and PowerPoint scan documents when they are opened and check for the existence of macros. If the document contains macros, the user running Excel or PowerPoint is alerted and asked if he would like the macros to be run. However, Microsoft Excel and PowerPoint may not detect malformed macros, so a user can unknowingly run macros containing malicious code when opening an Excel or PowerPoint document.
An intruder who can entice or deceive a victim into opening a document using a vulnerable version of Excel or PowerPoint could take any action the victim could take, including, but not limited to
- reading, deleting, or modifying data, either locally or on open file shares
- modifying security settings (including macro virus protection settings)
- sending electronic mail
- posting data to or retrieving data from web sites
For more information, please see
-
http://securityresponse.symantec.com/avcenter/security/Content/2001.10.04.html
- http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS01-050.asp
Given the strong potential for widespread abuse of this vulnerability, we strongly recommend that you apply patches as soon as you are able. For example, the Melissa virus which spread in March of 1999 used social engineering to convince victims to execute a macro embedded in a Microsoft Word document. For more information, see the CERT/CC Advisory listed below.
As a general practice, everyone should be aware of the potential damage that Trojan horses and other kinds of malicious code can cause to any platform. For more information, see
This vulnerability has been assigned the identifier CAN-2001-0718 by the Common Vulnerabilities and Exposures (CVE) group:
II. Impact
An attacker can execute arbitrary code on the target system with the privileges of the victim running Excel or PowerPoint.
III. Solution
Apply a patch
Appendix A contains information from vendors who have provided information for this advisory. We will update the appendix as we receive more information. If a vendor's name does not appear, then the CERT/CC did not hear from that vendor. Please contact your vendor directly.Until a patch can be applied, and as a general practice, we
recommend using caution when opening attachments. However, it is important to
note that relying on the "From" line in an electronic mail message is
not sufficient to authenticate the origin of the document.
This appendix contains information provided by vendors for this advisory. When vendors report new information to the CERT/CC, we
update this section and note the changes in our revision history. If a particular vendor is not listed below, we have not received their comments.Appendix A. - Vendor Information
Appendix B. - References
- http://securityresponse.symantec.com/avcenter/security/Content/2001.10.04.html
- http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS01-050.asp
- http://www.kb.cert.org/vuls/id/287067
- http://www.cert.org/advisories/CA-1999-04.html
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0718
The CERT Coordination Center thanks Peter Ferrie and Symantec Security Response, who discovered this vulnerability and published the information in their advisory. Additionally, we thank Microsoft Corporation, who published an advisory on this issue.
Author: Ian A. Finlay and Shawn V. Hernan.
Copyright 2001 Carnegie Mellon University.
Revision History
October 8, 2001: initial release October 11,2001: added information to systems affected section October 15,2001: revised systems affected section