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-------------------------------------------------------------- This story was printed from ZDNet Australia. --------------------------------------------------------------
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New vulnerability exposes Excel and PowerPoint macros By John McCormick, 0 October 29, 2001 URL: http://www.zdnet.com.au/news/software/soa/New-vulnerability-exposes-Excel-and-PowerPoint-macros/0,130061733,120261516,00.htm
Symantec's security response team has discovered that a carefully crafted document can bypass the normal macro protection provided by Microsoft Excel and PowerPoint even when the macro security configuration is set to High. Because this is a potentially serious vulnerability, we're going to discuss the harm it can cause and the product versions that are affected, as well as providing links to the fixes.
Symantec's discovery shows that a flaw in the Microsoft macro-checking routines Excel and PowerPoint use (but not the ones Word uses) enables some carefully crafted documents to bypass the security check. This allows the documents to be opened and any macros contained in the files to run automatically without first warning the user that a document contains macros. Applicability
The following versions of Microsoft Excel and PowerPoint for Windows and Macintosh are vulnerable:
The threat
Macros are powerful utilities that can be embedded in several types of Microsoft documents. These small programs can perform any task a user at the keyboard can initiate, including:
This vulnerability can bypass all the existing security settings related to macros in these documents because the software doesn't even detect the presence of a macro. The only protection left against this form of attack is reliance on a good security policy forbidding individual users to open any Excel or PowerPoint document from an unknown source. However, because most security policies tend to rely on the macro protection provided by the Excel and PowerPoint security model, which normally warns them if a document contains any macros, even people who are very security conscious may tend to be careless about opening these files. The fix
Microsoft recommends that all users apply the necessary patches immediately. A series of patches for various versions of the software is already available from Microsoft. See Microsoft
Security Bulletin MS01-050 for details and any recent updates to this
information, as well as the latest links to the patches.
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Malicious macros in Word, Excel, and PowerPoint files are a well-known security threat, and security personnel routinely configure office PCs to trigger a warning to users when a macro is present in a
document from an untrusted source.