One of the most dangerous and difficult to detect malware, a worm is a virus whose main characteristic is its ability to self-replicate
Not all malicious programs that enter computers are viruses, although in common usage we tend to use this term to identify any computer infection. The correct term to use in such cases would be malware, which means malicious software.
There are different malware, which change depending on the way it is targeted and the damage it does. In fact, a malicious software can overwrite the system code or delete all the files on the hard disk or steal the data contained in the infected device. Malicious programs infiltrate computers, and since a few years also smartphones, using various tricks: the goal is to deceive the victims. In most cases, the virus strikes because a distracted user has opened an email attachment or clicked on an unsafe link. Viruses also differ in the way they hide and spread.
The most dangerous and difficult to detect malware, once they have managed to get into the system, are worms.
The worm, the self-replicating worm
The worm is one of the most popular malicious programs that, like Trojan Horses, requires the unwitting cooperation of users. Generally, in fact, the worm sneaks into computers via an attachment or an executable script, contained in an e-mail message. Worms are able to camouflage themselves in the system and antivirus software, even though worms are extraneous programs, has a hard time finding them.
The main characteristic of a worm is its ability to self-replicate. The purpose of any type of virus is to hit as many victims as possible, and the worm, if it infects the machine, will access emails and send several copies of itself. And without the need for unintentional user intervention, as is the case with other viruses.
And that's not all. The most sophisticated worms can be used by hackers to strip the security system of the infected machine and install other malware. It is very common for them to be used for the installation of backdoors, i.e. "loopholes" in the computer's security network, or keyloggers, programs that store everything typed on the keyboard.
The worm is also often used to disrupt the affected machines, overloading the LAN with requests. We talk about DoS attacks, Denial of Service attacks.
How to defend yourself
To defend yourself from the worm you need to take some precautions. First of all, as we have seen, the virus spreads mainly via e-mail. Therefore, it is very important to pay attention to suspicious emails, avoiding opening attachments and clicking on unsafe links. Also, remember to keep your antivirus and your operating system updated.