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CERT Advisory CA-2001-28 Automatic Execution of Macros
Original release date: October 08, 2001
Last revised: -- Source: CERT/CC
A complete revision history can be found at the end of this file.
Systems Affected
Systems running:
* Windows
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.
http://www.cert.org/advisories/CA-1999-04.html
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
http://www.cert.org/advisories/CA-1999-02.html
This vulnerability has been assigned the identifier CAN-2001-0718 by the Common Vulnerabilities and Exposures (CVE) group:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0718
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.
Appendix A. - Vendor Information
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.
Microsoft Corporation
See Microsoft Security Bulletin MS01-050
Appendix B. - References
1. http://securityresponse.symantec.com/avcenter/security/Content/2001.10.04.html
2. http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/bulletin/MS01-050.asp
3. http://www.kb.cert.org/vuls/id/287067
4. http://www.cert.org/advisories/CA-1999-04.html
5. 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.
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Author: Ian A. Finlay and Shawn V. Hernan.
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This document is available from: http://www.cert.org/advisories/CA-2001-28.html