Microsoft today explained why it has not patched older versions of its Office for Mac, but would not disclose a release schedule for doing so.
"We cannot give an exact date, but we expect to provide these updates during one of our normal monthly update cycles very soon," said Jerry Bryant, a group manager in the Microsoft Security Response Center (MSRC).
Bryant was responding to questions raised Tuesday when Microsoft issued a multi-patch update for all versions of Office on Windows, including Office XP, 2003, 2007 and 2010, and Office for Mac 2011.
However, Microsoft did not deliver patches for the vulnerabilities in Office for Mac 2004 and Office for Mac 2008.
"The updates for Mac Office 2004 and 2008 were not ready for broad distribution at the same time as the updates for the affected products used by the vast majority of our customers," said Bryant in an e-mail reply to Computerworld queries.
The majority of Office users run the Windows editions of the suite, which greatly outsells the same software for Mac OS X.
According to the MS10-087 security bulletin associated with the Office updates, Office 2007 and Office 2010 users are most at risk because attackers can hijack their machines simply by getting them to view a specially-crafted message in the Outlook preview pane.
In a second e-mail Wednesday, Bryant said that Office for Mac users were not vulnerable to the same types of attacks, although hackers could try to dupe them into opening malicious RTF (rich text format) documents attached to e-mail messages.
Microsoft has delayed security updates for the Mac version of Office before.
In May 2009, Microsoft shipped patches for the Windows version of PowerPoint -- Office's presentation maker -- but delayed fixes for the same flaws in its Mac software until the following month.
At the time, Microsoft's security team defended the decision by saying that fixes for Windows were finished, but were still being tested on the Mac.
Today, Bryant said it was a matter of priorities, both in the number of users running Windows software compared to the Mac, and in the threat posed to each group. "Normally, we release updates for all affected products at the same time, [but] in cases where the vast majority of our customers are at potential risk and we can provide protections, we may decide to release updates for those products, if ready, ahead of products where the risk is very low," he said.
Last year, Microsoft took heat over the PowerPoint patch delay, with one security expert saying it put Mac users at risk. Others agreed with Microsoft's decision at the time.
Today, HD Moore, the chief security officer at Rapid7 -- and the creator of the popular Metasploit penetration toolkit -- dissed Microsoft's decision, up to a point.
"It's a bit surprising because on one hand they're giving away the key," he said. "The information in Microsoft's security bulletins isn't remotely useful to researchers, but now they're free, since Microsoft has officially patched the vulnerabilities [in Windows and Office for Mac 2011], to disclose technical information to the public."
On the other hand, said Moore, it's unlikely that anyone will take the patched Office for Mac 2011, then reverse engineer the fix to uncover the specific flaws in Office for Mac 2004 or 2008. "It's a pain in the ass to reverse engineer Office," said Moore, talking about the process often used by researchers, both legitimate and criminal, to figure out how to exploit a vulnerability
Unlike a typical patch for Windows, which may reside in just a single revamped DLL, or dynamic link library, fixes for Office are included in a massive, recompiled executable, or EXE file. "There could be 30,000 changes in that EXE," said Moore.
And it's not as if Mac owners aren't used to being treated as second-class citizens when it comes to patches, Moore added.
"Apple has been doing this for years," he said. "It often takes Apple months to update components in Mac OS X, such as Samba, after they've been patched, even when exploits have been released."
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is email@example.com.