Macro malware in Word and Excel: A practical guide for contract reviewers

As a contract reviewer, you probably spend most of your time working with Word and Excel documents. Whether you’re redlining agreements, analysing contract data, or tracking changes, your workflow relies heavily on Microsoft Office. But this dependence on Word and Excel also makes you a prime target for cybercriminals using macro malware—one of the most common attack vectors in contract-heavy industries like legal, finance, and procurement.

Understanding how macro malware works and how to defend against it is essential to protect confidential data, maintain integrity in contract review processes, and avoid business disruptions. Here’s what you need to know.

What is macro malware, and how does it work?

Microsoft Word and Excel use macros, which are small programs written in Visual Basic for Applications (VBA) to automate repetitive tasks. While macros can be helpful for formatting contracts or running calculations, they can also be exploited to deliver malware.

How a macro-based attack typically happens

1. You receive an email with an attached Word or Excel file – often disguised as a contract, invoice, or legal document.
2. The email urges you to enable macros – claiming it’s necessary to view the document properly. Messages may say:
   • “Enable macros to see all changes.”
   • “This document is protected. Click ‘Enable Content’ to view it.”
3. If you enable macros, malicious code executes in the background, performing actions such as:
   • Downloading malware to your system
   • Stealing confidential contract data
   • Spreading malware to other documents or users

Why are contract reviewers at risk?

• Frequent email exchanges with clients, colleagues, and vendors.
• Handling third-party documents—which may contain hidden macros.
• Trusting familiar-looking documents—since legal and contract workflows involve structured forms and templates.

Practical steps to stay secure on Windows

1. Disable macros by default

Microsoft disables macros in downloaded documents by default, but it’s easy to accidentally enable them. Ensure macros remain disabled unless absolutely necessary.

Check your settings

1. Open Word or Excel.
2. Go to File → Options → Trust Center → Trust Center Settings.
3. Click macro settings and select:
   • “Disable all macros with notification” (default) – best for general users.
   • “Disable all macros without notification” – best for strict security environments.

Never enable macros in a document unless you are 100% sure it’s safe.

2. Use ‘Protected View’ for documents from external sources

Protected View opens documents in a read-only mode to prevent malicious macros from running.

How to enable Protected View

1. Go to File → Options → Trust Center → Trust Center Settings.
2. Select Protected View and make sure these options are checked:
   • Enable Protected View for files originating from the internet
   • Enable Protected View for files located in potentially unsafe locations
   • Enable Protected View for Outlook attachments

If a contract needs editing, save a copy and scan it for threats before enabling full editing mode.

3. Be cautious of email attachments

Most macro malware spreads through phishing emails disguised as contract requests or vendor agreements.

Spot phishing attempts

• Unexpected contract documents from unknown senders.
• Emails with urgent or threatening language (e.g., “Respond within 24 hours to avoid penalties”).
• Attachments with suspicious file names (e.g., “urgent_contract_2024.xlsm”).
• Poor grammar or strange email formatting.

Never open or enable macros in unexpected attachments.

4. Check for suspicious macros in documents

Even if you trust the sender, reviewing the macros before enabling them is a good security habit.

How to check macros in Word and Excel

1. Open the document.
2. Press ALT + F11 to open the VBA Editor.
3. Look for unexpected code or references to external websites.
4. If you see unfamiliar or obfuscated code, do not enable macros.

If in doubt, ask IT before enabling macros.

5. Keep your software and antivirus updated

Microsoft regularly patches security vulnerabilities, so running outdated versions increases risk.

Best practices

• Keep Microsoft Office and Windows updated to the latest security patches.
• Use endpoint protection software that detects and blocks macro malware (e.g., Microsoft Defender, Bitdefender, CrowdStrike).

Avoid using pirated or outdated Office versions, as they may lack security updates.

6. Convert documents to PDF when possible

If you only need to review a contract without making edits, request a PDF copy instead of a Word or Excel file.

• PDFs are less likely to carry macro malware (but still check for embedded scripts).
• If you must edit a contract, avoid macro-enabled formats like .docm or .xlsm.

What if you’re using a Mac?

While macro malware is more common on Windows, Mac users are not immune.

Mac-specific risks

• Office for Mac supports VBA macros, meaning infected documents can still execute malicious code.
• Mac malware is less common but harder to detect, as many people believe macOS is immune.

Mac security tips

Disable macros in Office for Mac

• Open Word/Excel → Preferences → Security & Privacy
• Uncheck “Enable all macros” and ensure “Warn before opening macros” is checked.

Use Protected View

• Open external files in read-only mode before enabling editing.

Keep macOS and Office updated

• MacOS’s Gatekeeper and XProtect block known threats, but regular updates are crucial.

Use a Mac-specific antivirus

• Consider Malwarebytes for Mac or Intego for additional protection.

Never enable macros unless necessary—Macs can still be compromised.

What to do if you suspect a macro malware attack

1. Immediately disconnect from the internet – to prevent further data theft or malware downloads.
2. Alert your IT team – they can isolate and scan your device.
3. Run a full system scan using a trusted antivirus program.
4. Change passwords for critical accounts if you suspect credential theft.

Final thoughts: Security without sacrificing productivity

Contract reviewers handle confidential, high-value documents, making them a target for macro malware attacks. But staying secure doesn’t mean sacrificing efficiency.

By following these best practices—disabling macros by default, using Protected View, verifying attachments, and keeping software updated—you can significantly reduce your risk while continuing to work effectively.

A few extra seconds of caution can save you from a data breach, financial loss, or legal liability. Stay vigilant and review contracts safely!