What is a Worm?

A worm in cybersecurity is a standalone malware computer program that replicates itself to spread from one computer to other devices.

A worm leverages security loopholes to access a target system. Once a worm reaches one computer in a network, it uses the machine as a host to scan and infect other computers. It uses a computer network to spread.

Key Takeaways

  • A worm is a malware program that self-replicates to spread from one device to another
  • A worm relies on the security gaps to reach a target system
  • The malicious program uses a computer network to spread from one computer to another
  • A computer work uses both recursive method and law of exponential growth to replicate and distribute in a system
  • A worm is independent, complex, contagious, and can potentially exploit existing vulnerabilities in systems
  • Security professionals also create and spread anti-worm to research and prevent systems from malicious worms
  • You can prevent worms by updating operating systems, avoiding opening links on emails, and installing updated antivirus and firewall

How Does a Worm Work?

A computer worm uses a recursive method to copy themselves without a host program and distribute based on the law of exponential growth.

Computer worms rely on the actions of network protocols to propagate. The malicious programs also exploit existing vulnerabilities in systems. For instance, the WannaCry incident exploited a vulnerability on the Server Message Block (SMBv1) resource sharing protocol in Windows Operating System. Users also get infected by opening email attachments or visiting malicious webpages. 

Once active on a newly infected computer, a worm initiates a network search for potential victims, allowing the program to propagate within an organization. If a company allows “bring your own device (BYOD) policy,” the worm can spread from work to home networks, giving cybercriminals even more access.

Impact of a Computer Worm?

A worm almost always causes some adverse impact on the target.

  • A computer worm consumes the target computer bandwidth
  • The malicious programs corrupt or modify files in a computer
  • A worm can exfiltrate confidential data such as passwords
  • Some worms may install a backdoor that allows hackers to control computers remotely
  • A worm allows criminals to commit other harm like sending spams or performing denial of service attacks using the host machine

What are the Features of a Worm?

  1. Independence – a worm is an independent program or code chunk that does not require a host program. Malicious programs can run independently and actively cause attacks.
  2. Exploit Attacks – since a host program does not limit a computer worm, the malicious tool can take advantage of different operating system vulnerabilities to cause active attacks.
  3. Complexity – cybercriminals create worms that integrate with web page scripts and hide in HTML pages using technologies like VBScript and ActiveX. An unsuspecting user triggers the worm by visiting a webpage containing the malicious program.
  4. Contagious – worms are highly infectious as compared to a traditional virus. They infect local computers, servers, and clients on a network. The malicious programs easily spread through shared folders, infected webpages, emails, and vulnerable servers. Worms also spread through software vulnerabilities

Can a Worm Have Good Intent?

Some worms, commonly referred to as anti-worm, are helpful. The programs are designed to do something useful to the user. However, you should get the target’s consent before executing an anti-worm on their computers.

What are the uses of an anti-worm?

  • System Tests: Authors and security experts create helpful worms to test the network. You can develop an anti-worm to exploit vulnerabilities to make systems secure.
  • Research: Some researchers create helpful worms to research how worms spread. You can design an anti-worm to test the effects of changes in user behavior and social activity.
  • Security Tools: Some anti-worms help security analysts to combat the effects of other malicious worms like Blaster, Code Red, and Santy. Welchia is an example of a helpful worm that utilizes the same deficiencies exploited by the Blaster worm. Welchia infected computers to automatically download and install Microsoft security updates for Windows without user interaction. The updates patched the systems to fix the exploit that Blaster targeted.

How Can I Tell if My Computer has a Worm?

You can run a virus scan to determine if your computer has a worm. You can also detect worms through the following steps:

  • Keep an eye on your computer hard drive space. Worms self-replicate and use up space in your device
  • Monitor your system speed and performance. If your computer is sluggish and programs are crashing, that is a red flag, and the worm might be eating up your processing resources
  • Be vigilant to detect missing or new files. A computer worm can delete or replace files in your hard drive.

How Can I Prevent Worms?

  • Update the OS: As mentioned, worms spread by exploiting existing vulnerabilities in operating systems. install regular security updates to prevent worms from exploiting security flaws
  • User Awareness: Avoid opening unexpected emails and attachments. Do not visit website links on emails before confirming the sender.
  • Use Security Tools: Install updated antivirus and antispyware programs that automatically scan, detect, and prevents worms. You can also use firewalls that monitor and block malicious network traffic.