Microsoft apps on macOS could be your biggest privacy threat

Microsoft apps like Word, Excel, Outlook and Teams are so popular (and useful) that they’re nearly unavoidable, whether you’re on a Windows computer or a Mac. However, these apps can become a hacker’s paradise on Apple Macs due to an unpatched vulnerability.

A cybersecurity research group has revealed that Microsoft apps on Macs have a security flaw that could allow hackers to access your photos, videos, contacts and almost all of your private data. 

The worst part? Microsoft doesn’t consider it a big enough threat to fix.

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The cybersecurity research group Cisco Talos has discovered security vulnerabilities in Excel, OneNote, Outlook, PowerPoint, Teams and Word. These vulnerabilities allow attackers to inject malicious libraries into these apps, giving them access to the apps’ permissions and user-granted entitlements.

To understand why that’s dangerous, let’s first look at macOS’s framework. Mac devices operate on a permission-based system and rely on the Transparency, Consent and Control (TCC) framework. You’ve probably noticed that every time you download a new app, you’re asked to grant permission for it to run. Similarly, when an app wants to access sensitive information like contacts, photos or webcams, you’re prompted to allow or block access.

This system ensures that you know and trust the apps that have access to your private information. However, Apple doesn’t allow just any app to request access to sensitive data — only those with the proper entitlements, meaning apps that Apple has authorized to make such requests. Apps without these entitlements won’t prompt you for permission to access sensitive data.

The Microsoft apps mentioned above have these entitlements, and the security flaw within them allows hackers to bypass permission requests and access your sensitive information.

"We identified eight vulnerabilities in various Microsoft applications for macOS, through which an attacker could bypass the operating system’s permission model by using existing app permissions without prompting the user for any additional verification," the researchers explain.

For example, a hacker could design malicious software to read your emails or view your browsing history without you even knowing. "All apps, except for Excel, can access sensitive data like your emails and web activity," the group adds.

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Microsoft considers the security flaws "low risk" and has declined to fix them in some apps. "Microsoft considers these issues low risk, and some of their applications, they claim, need to allow loading of unsigned libraries to support plugins and have declined to fix the issues," the Cisco Talos research group said.

Microsoft updated the Teams and OneNote apps on macOS to change how they handle the library validation entitlement. However, Excel, PowerPoint, Word and Outlook remain vulnerable to the exploit.

Cisco Talos hasn’t provided a working example of how this vulnerability could be exploited in real-world attacks. They also haven’t confirmed whether hackers have used the flaw to access users’ sensitive information yet.

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We reached out to Microsoft, and a company spokesperson offered this statement:

"The disclosed cases do not pose a significant security risk as the technique described requires the attacker to already have a certain level of access to the system. However, we have implemented several updates for added protection, as detailed in the report. As a best practice, customers should keep their software updated and regularly review application permissions." 

We also contacted Apple but did not hear back by our deadline. 

There’s not much you can do to protect yourself in this situation unless Microsoft patches the vulnerability. Still, below are some steps you can take to minimize the risk.

1. Keep your apps updated: Regularly check for updates to your Microsoft apps through the Mac App Store or the Microsoft AutoUpdate tool. Even though not all vulnerabilities may be addressed, updates often include important security patches that reduce your risk of exploitation.

2. Limit permissions: Go to your macOS settings and review the permissions granted to Microsoft apps. Disable access to sensitive data like your camera, microphone, contacts, and calendar unless absolutely necessary. For example, if you rarely use the camera in Teams, you can revoke its access. Here's how to do it:

For earlier macOS versions, the steps to limit permissions for Microsoft apps are slightly different. Here’s how you can do it:

These steps help ensure that Microsoft apps on your macOS have limited access to sensitive data, enhancing your privacy and security.

3. Consider alternatives: If you’re concerned about security, consider using alternative office software that is less susceptible to these vulnerabilities. Apple's suite of productivity apps, including Pages, Numbers and Keynote, are designed specifically for macOS and offer robust security features. These apps can serve as viable replacements for Word, Excel and PowerPoint, respectively.

Additionally, Google Workspace offers cloud-based tools like Google Docs, Sheets and Slides, which are accessible from any device and provide strong security measures. By switching to these alternatives, you can reduce the risk of unauthorized data access and maintain better control over your personal information.

4. Use strong antivirus software: The best way to safeguard yourself from malicious links that install malware and potentially access your private information on your Mac is to have antivirus software installed on all your devices. This protection can also alert you to phishing emails and ransomware scams, keeping your personal information and digital assets safe. Get my picks for the best 2024 antivirus protection winners for your Windows, Mac, Android and iOS devices.

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While Microsoft apps like Word, Excel, Outlook and Teams are indispensable tools for many, their vulnerabilities on macOS pose significant security risks. The discovery highlights how these apps can be exploited to access sensitive data without your consent. Despite the seriousness of these findings, Microsoft's decision not to address all vulnerabilities leaves you in a precarious position. It's crucial for you to stay vigilant by keeping your apps updated, limiting permissions and considering alternative software solutions to safeguard your data. As technology evolves, so do the threats, making it essential for you to prioritize security.

How should Microsoft take responsibility for ensuring your security and privacy in light of identified vulnerabilities in its applications? Let us know by writing us at Cyberguy.com/Contact

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