What is Melissa virus?

The Melissa virus is a macro virus that infects devices through email attachments and then sends copies of itself through an infected user’s email account.

Named after an exotic dancer mentioned in the virus code, the Melissa virus was released by an American programmer named David Lee Smith in 1999. Smith had hijacked an AOL account and posted a file called “alt.sex.” to an online group. The virus began replicating and spreading by sending the same infected email to the first 50 contacts in the user’s address book.

What is a macro virus?

A macro virus is a type of malware that infects software that runs macros, such as Microsoft Office applications. These viruses embed themselves in the macro scripts of documents or spreadsheets, executing malicious code when the file is opened. Macro viruses can spread rapidly through shared documents and email attachments.

They often require user interaction to activate, such as enabling macros in a document. Once activated, macro viruses can perform various harmful actions, including corrupting data, spreading to other systems, or installing additional malware.

How does the Melissa virus work?

The Melissa virus spreads through email attachments, often disguised as an essential document. The virus first confirms that Word 97 or Word 2000 is installed. When the user opens the infected attachment, typically a Microsoft Word document, the virus activates and runs a macro script embedded within the document.

While primarily designed to spread rapidly, the Melissa virus can corrupt files by inserting random text into Word documents on the infected machine. Lastly, the macro script extracts email addresses from the infected user’s Microsoft Outlook address book.

The impact of the Melissa virus

As one of the first widely publicized macro viruses, it exploited Microsoft Word and Outlook to propagate rapidly via email, causing major global disruptions across businesses and individuals. The virus sent out over 300 million emails, overloading the email servers of over 300 businesses and government agencies. According to the FBI, the virus cost approximately $80 million due to the disruptions, repairs and recovery efforts needed.

Beyond the immediate technical and financial repercussions, the Melissa virus was a crucial turning point for IT security. It highlighted the need for IT professionals to keep their IT environments secure and for organizations to educate users about common infection tactics such as phishing.

How to protect yourself from macro viruses

1. Monitoring

For MSPs and IT teams, full visibility of user activities and device health can help pinpoint suspicious activity or potential vulnerabilities. A remote monitoring and management (RMM) solution could help bolster an organization’s defenses against macro viruses.

2. Automated patch management

Ensure all applications and operating systems are regularly updated with security patches. Patch management solutions can help keep all software and operating systems in an IT environment up to date. IT automation can further streamline the patching process by auto-detecting missing patches and scheduling the deployment of updates.

3. Keep your antivirus software updated

Install reputable antivirus software on your devices and ensure they are regularly updated. Implementing a robust antivirus enables IT security professionals to detect and remove macro viruses.

4. Enable macro security settings

In applications like Microsoft Office, set macro security settings to high or very high. This will disable macros from running automatically without your authorization.

5. Backup data regularly

Maintain regular backups of sensitive and vital data. A backup solution can help you recover your data during disasters, cybersecurity breaches, and other data loss events.


The Melissa virus highlighted the critical need for proactive IT security measures due to the substantial financial loss and operational disruptions.IT professionals and businesses. For IT security professionals, the lessons from the Melissa virus are clear. Implementing robust security measures such as regularly updating endpoint devices allows technicians better to protect IT environments from cyberattacks in the future.

Ready to become an IT Ninja?

Learn how NinjaOne can help you simplify IT operations.

Watch Demo×

See NinjaOne in action!

By submitting this form, I accept NinjaOne's privacy policy.

Start a Free Trial of the
#1 Endpoint Management Software on G2

No credit card required, full access to all features