Crush that Worm before It Creeps into Your Computer

McAfee

Nov 17, 2025

7 MIN READ

Some years ago, a highly infectious computer worm called W32/Autorun was discovered to be infecting Windows computers. Unlike a virus, a worm such as W32/Autorun doesn’t steal anything from your computer. Instead, it spreads rapidly and opens as many security holes as possible to allow hackers to install a different form of malware that will eventually steal information, money, or both.

While this worm is less widespread today, it continues to infect older Windows operating systems that are not regularly updated. This guide will take a closer look at how the worm spreads and outline preventive measures to avoid infection.

Older Windows versions at risk

Autorun worms primarily affect older Windows systems such as Windows XP, Vista, and early versions of Windows 7, which had AutoRun enabled by default. Microsoft recognized this security vulnerability and significantly restricted AutoRun capabilities in newer Windows versions, but millions of older systems remain at risk if they haven’t been properly updated or configured.

When an autorun worm infects your system, it can compromise both your files and privacy in several ways by stealing personal documents, capturing passwords and banking information, or installing additional malware that monitors your online activities. Some variants encrypt your files for ransom, while others turn your computer into part of a botnet used for spam or cyberattacks. The infection can also spread to family members, friends, or colleagues when you share USB drives or connect to shared networks.

While this worm is less common today due to security updates in newer Windows operating systems, the concept of autorun malware is still relevant, often evolving into new forms that spread via malicious downloads, USB drives, or network shares. These forms use clever file drops and social engineering, with detection still relying on robust antivirus and user caution.

Key ways W32/Autorun bypasses your computer’s defenses

W32/Autorun is effective because it exploits everyday behaviors and outdated system features. Instead of forcing its way into your computer, it relies on built-in Windows functionality and simple tricks to get users to let it in, slip past basic defenses, and infect systems.

Easy way in via Windows AutoRun

An autorun worm spreads, as its name suggests, automatically through removable storage devices such as USB drives, external hard drives, and network shares. It takes advantage of Windows’ AutoRun and AutoPlay features to secretly execute itself when you connect the removable device to your computer that has AutoRun. A dialog box then pops up asking if you want to automatically run whatever is on the device. When you unsuspectingly click “run,” you’ve authorized the W32/Autorun worm. Once active, the worm copies itself to other connected drives and network locations, rapidly spreading to any system. While this feature was not included in Windows 8 for security reasons just like this, it still exists on many older machines that haven’t been updated in a while.

Fake folders lure victims in

Even if you don’t have Windows AutoRun enabled in your device, W32/Autorun disguises itself as interesting imposter files and folders with names like “porn” and “sexy” in infected flash drives or shared internet connections to trick you into downloading the worm. Once you click on the malicious file, it executes AutoRun and infects your computer.

The worm can also change your computer’s settings to allow it to run every time you boot up. Some variants even disable Windows updates to prevent the system from downloading security patches and ensure the worm can do its job of infecting every device your computer comes into contact with, opening the door for any virus a hacker wants to install at your expense.

Symptoms of a W32/Autorun worm infection

A W32/Autorun worm infection works quietly in the background, spreading to connected devices and weakening your system’s defenses without triggering immediate alarms. However, there are subtle signs that indicate the infection. Recognizing these early symptoms can help you take action to block the worm’s activities before it causes irreparable damage to your device and network:

Slow performance: Your computer or internet connection may slow down due to the high processing usage that the worm requires as it actively searches for drives to infect.
Presence of unfamiliar files/folders: The worm creates copies of itself and configuration files on infected drives, sometimes disguised with random names or enticing names such as “porn” or “sexy”.
System instability: Your computer may begin freezing, crashing, or restarting unexpectedly as the worm runs multiple background processes while consuming system resources and interfering with normal operating functions.
Modified settings: You might notice unexpected changes to your desktop, folder views, or system preferences without your input. These modifications are often made to hide malicious files or make it easier for the worm to run automatically.
Loss of access to some features: Tools like Task Manager, Registry Editor, or Folder Options may suddenly become inaccessible. The worm disables these features to prevent you from stopping its processes or removing it manually.
Disabled antivirus software or Windows updates: Your security software may stop working properly, or Windows updates may be turned off without explanation. This enables the worm to block security patches and scans that could remove it.
Unusual network activity: You may notice unexplained internet traffic even when you’re not actively using your device. The worm could be contacting remote servers to report successful infections or download additional malicious components.
Diminished storage space: Available disk space may shrink rapidly with no clear reason. This happens because the worm repeatedly copies itself across your system and connected drives.

Consequences of the W32/Autorun worm

The impact of the W32/Autorun worm can vary depending on the specific variant, ranging from minor annoyances to severe system compromise:

System damage and further infection: The W32/Autorun worm acts as an entry point for attackers to silently install more dangerous malware, including data-stealing Trojans or destructive viruses.
Data loss and corruption: Some variants can delete important files or corrupt stored data, making documents, photos, or applications unusable or permanently unreadable, even after the worm is removed.
Disruption of operations: Because the worm consumes large amounts of processing power and memory in the background, it can slow down your device’s performance and stall programs to make daily computing tasks difficult.
Unauthorized access and information theft: Certain W32/Autorun variants are capable of monitoring your online activity, including logging keystrokes, capturing login credentials, and stealing financial details or personal data.
Aesthetic changes: Less destructive versions of the worm may focus on annoying changes such as altered desktop backgrounds, browser settings, or system appearance.

How to Prevent a W32/Autorun Infection

Preventing a W32/Autorun infection is largely about closing the simple security gaps the worm relies on to spread. By taking these steps, you can significantly reduce the chances of this worm gaining access to your computer.

1. Disable AutoRun

If your computer is still prompting you to automatically run applications each time you insert a CD, connect to a new network, or plug in a flash drive, update your computer as soon as possible. Visit the Microsoft website to learn how to disable AutoRun for your specific version of Windows.

2. Beware of shared removable devices

Remember that this worm is highly infectious. If you share a flash drive with a friend whose computer is infected, that flash drive will carry the worm to your computer. If you do need to share a device, make sure AutoRun is disabled before you plug it in, and check that your security protection has the capability to scan new drives to prevent you from clicking on infected files.

3. Use reliable antivirus

While the first two tips focus on prevention, a reliable security solution will not only prevent a W32/Autorun infection, but also remove it from your computer. Solutions like McAfee+ will catch the W32/Autorun worm bug and other similar malware, protecting you from accidentally spreading it to friends and family.

Final thoughts

Autorun worms represent a persistent threat that combines old vulnerabilities with modern attack techniques. Newer security measures may have reduced their impact, but these worms continue to target systems with outdated configurations through the continued use of removable media. This is why keeping systems updated and being cautious with external devices are important habits to apply.

In addition, you can protect yourself with proper security practices: disable AutoRun on older systems, keep your antivirus software updated, scan external devices before accessing their contents, and avoid connecting unknown USB drives to your computer.