What Is a Computer Worm?

CryptographySystem SecurityEthical Hacking

Computer Worm

A worm is a harmful software (virus) that repeats itself as it moves from computer to computer, leaving copies of itself in each computer's memory. A worm finds a computer's vulnerability and spreads like an illness throughout its associated network, constantly looking for new holes. Worms, like viruses, are spread by email attachments from seemingly trustworthy senders. Worms then propagate through a user's email account and address book to contacts.

Some worms reproduce and then go dormant, while others inflict harm. The worm's code is referred to as payload in such circumstances.

How do they work?

Computer worms make use of network flaws to spread. The worm is hunting for an unobserved back door into the network. To spread computer worms for the first time, hackers usually send phishing emails or instant chats with malicious attachments. The worm is disguised by cyber thieves so that the recipient is willing to run it. For this aim, duplicate file extensions and a data name that appears harmless or urgent, such as "invoice," are utilized. When the user opens the attachment or clicks on the link, the malware (computer worm) will be downloaded into their system or lead to a harmful website.

As a result, the worm enters the user's system without their knowledge. After being terminated, the worm looks for a way to duplicate itself and infiltrate new computers. For example, the worm can send an email to all contacts on the infected machine, which contains worm replication. A payload is a feature that many worms currently have. The term "payload" refers to the "payload" and, in this example, an attachment that the worm carries. The worm can, for example, has ransomware, viruses, or other malware, all of which can harm afflicted computers. In the event of a blackmail assault, these can, for example, remove or encrypt files on the PC.

A computer worm can also create a back door that other malicious programs can use later. This flaw allows the worm's creator to take control of the infected computer. Meanwhile, malware operations frequently use a combination of several malware types. Take the WannaCry ransomware or the Petya / Not-Petya ransomware, for example. These include a worm component, which allows the virus to replicate and spread through back doors in other network systems.

Because the worm or its programmer can use the infected system's computing capacity, they are frequently integrated into a botnet. Cyber thieves then employ these, for example, in DDoS assaults or crypto mining.

What are the types of computer worms?

Malicious computer worms come in a variety of forms −

Email worms

To spread, email worms create and send outbound messages to all addresses in a user's contact list. When the recipient opens the mail, it contains a malicious executable file that infects the new system.

Successful email worms typically use social engineering and phishing approaches to persuade users to open the linked file.

File-sharing worms

File-sharing worms are malicious programs that hide as media files.

Stuxnet, one of the most well-known computer worms of all time, comprises two parts: a worm that spreads malware via USB devices infected with the host file and malware that targets supervisory control and data acquisition systems. Industrial contexts, such as power utilities, water supply services, and sewage plants are frequently targeted by file-sharing worms.


Cryptoworms encrypt data on the victim's computer system. This worm can be used in ransomware attacks, in which the attackers contact the victim and seek payment in exchange for a key to decrypt their files.

Internet worms

Some computer worms are designed to attack prominent websites that have weak security. They can infect a computer viewing the website if they can infect the site. Internet worms then propagate to other devices connected to the infected PC via internet and private network connections.

Worms that spread via instant messaging

Instant messaging worms, like email worms, are disguised as attachments or links, which the worm uses to spread throughout the infected user's contact list. The only difference is that it comes as an instant message on a chat site rather than an email.

If the worm hasn't had time to replicate itself on the machine, it may usually be stopped by resetting the user's chat service account password.

Virus vs. computer worm

Because they behave similarly, some people mistakenly believe that a computer worm and a computer virus are the same things. They might even call it a "worm computer virus" or "worm virus malware." The truth is that the two threats are similar yet distinct.

The major distinction between a virus and a worm is that viruses require human action to activate, whereas worms replicate only in the presence of a host system. In other words, unless you run a virus, your computer will not be harmed. A virus on a flash drive connected to your computer, for example, will not harm your system unless you activate it. A worm, as previously stated, does not require a host system or user input to spread.

What kind of harm may a computer worm do?

A worm may not do any harm at all: in the early days of computing, worms were often developed as pranks or demonstrations of concept to exploit security flaws. They did little more than reproducing themselves in the background on afflicted machines. When the worm made too many copies of itself on a single system and slowed down its activities, it was often the only way to notice something was wrong. Worms became a means to an end when OS security increased and building a worm that could breach it became more difficult and time-consuming.

Nowadays, worms almost always incorporate payload code that performs more than the worm's reproduction and propagation. There are numerous distinct forms of computer worms that cause various kinds of damage to their victims. Some transform computers into "zombies" or "bots" that launch DDoS attacks; others search their hosts for banking logins or other sensitive financial information, and still, others encrypt the victim's hard drive and demand a bitcoin ransom before restoring their data.

The infection vector is another approach to classify different types of worms. Email worms, instant messaging and IRC worms, file-sharing worms, and internet worms fall under this category, looking for any opportunity to propagate.

How to prevent worms?

Malicious software can take many forms, including computer worms. Take these measures to help protect your computer against worms and other internet threats.

  • Because software vulnerabilities are a common source of infection for computer worms, make sure your computer's operating system and programs are up to date. Because updates frequently include patches for security problems, install them as soon as they become available.

  • Another popular method for hackers to transmit worms is through phishing (and other types of malware). When opening unwanted emails, be particularly cautious, especially those from unknown senders that include attachments or questionable URLs.

  • Make sure you have a good internet security software solution to help you block these dangers. Anti-phishing technologies, as well as defenses against viruses, spyware, ransomware, and other online threats, should be included in a solid solution.

Updated on 15-Mar-2022 11:44:39