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Microsoft Reverses Course on Blocking Office Macros by Default

Security experts criticize company for reversing course, albeit temporarily, on a decision it made just this February to block macros in files downloaded from the Internet.

Updated 5:19 p.m. EDT to include Microsoft's clarification that the change is temporary. 

Several security experts expressed disappointment this week at Microsoft's quiet reversal Wednesday of a decision it had announced in February to disable Office macros in files from the Internet. Likely in response, Microsoft on Friday clarified that the rollback is only temporary while the company makes some additional changes to enhance usability.

In a brief — and barely noticeable — update Wednesday to the February announcement, the company originally said it was taking the step because customers wanted it to do so. "Based on feedback, we're rolling back this change from Current Channel," Microsoft said. "We appreciate the feedback we've received so far, and we're working to make improvements in this experience."

On Friday, the company revised the wording to make clear the rollback was not permanent. "This is a temporary change, and we are fully committed to making the default change for all users," Microsoft noted. The update noted that organizations that wanted to could block Internet macros through the Group Policy setting.

Macros allow users to automate commonly repeated tasks in Microsoft applications such as Word, PowerPoint, and Excel. But they have also long been a favorite attack vector for threat looking to deploy ransomware and other malware on Windows systems via phishing emails and other means. As a glaring example: in January 2022, just before Microsoft announced its decision to block macros from running by default, some 31% of all threats that Netskope blocked involved weaponized Office files.

"Macros in Microsoft Office have been a mixed blessing since their inception," says Mike Parkin, senior technical engineer at Vulcan Cyber. "While they provide a lot of functionality that users like and have leveraged in myriad ways, they’ve also been a popular attack vector since they were introduced."

Microsoft's February announcement that they were doing something about macros as an attack vector was welcomed by people in cybersecurity. So, its change of heart now is a bit disappointing, Parkin says. "While Microsoft has not yet said why they are rolling back the change, it seems likely it’s because users have come to depend on the functionality and would rather keep it in spite of the risk."

A Microsoft spokesman pointed Dark Reading to the company's updated update on the rollback when asked for comment.

The Macro Threat

Microsoft itself has noted the threat that macros pose. In fact, as recently as April, the company urged Windows administrators to ensure Office macros are disabled in the environment to protect against macro malware. The company pointed to several ransomware families that attackers had distributed on Windows systems by abusing macros. Because of this, many security experts reacted with enthusiasm when Microsoft announced that macros from the Internet would be blocked by default in Office starting April 2022.

Starting with Office version 2203, users would no longer be able to enable content macros in files from the Internet by clicking a button, Microsoft had said. Instead, when they attempt to open a download or attachment from the Internet, a message would alert users them about the presence of VBA macros in the file and direct them to learn more about the potential risks associated with the file.

The change prompted a noticeable drop in Office-based attacks. According to Netskope, the percentage of Office malware detected by the company's cloud security platform has declined steadily since February 2022 and hovered at less than 10% for the last five months — compared with 35% a year ago.

Microsoft's reversal this week is going to result in a resurgence of Office malware, says Ray Canzanese, director of Netskope Threat Labs. "We are disappointed with the decision," Canzanese says. "Malicious Office documents are a major infiltration vector for attackers, being used to spread backdoors, info stealers, and ransomware."

Microsoft's decision suggests the company decided to prioritize the usability concerns of a vocal minority of customers over the security benefits inherent in disabling macros by default for all Office users, he says. "Instead of having users who preferred the old behavior opt-out of the enhanced security measure, users and admins will now have to opt-in," Canzanese says. "With this reversal, we expect Office documents to regain their previous popularity among attackers."

Ian McShane, vice president of strategy at Arctic Wolf, says disabling Office macros by default was a huge step forward in securing a tried and tested attack path for adversaries. Re-enabling macros now means Office users are less secure today than they were a week ago. McShane says it would have been better for Microsoft to have continued blocking macros by default than leaving it up to organizations to do it. via group policy settings. The multiple steps and settings that are often involved in doing this can be confusing, he says. 

Instead, the better approach would have been to let those who need macros to enable it via group settings. "Opt-in security benefits no one and is dangerous," he says.