What is a worm and a virus


1. term: A computer worm (in the following for short: worm) is a computer program or script (or script file, contains interpretable commands of a scripting language) with the property of reproducing itself after it has been executed. A worm is a hacking technique and belongs to the group of malware.

2. content: Worms are complete programs whose habitat is computer networks. They spread via networks or via removable media such as USB sticks. A worm can send a copy to other computers. For this purpose, he must know the protocol of the respective network and be able to inspect the address list in which the individual node computers of the computer are recorded.

3. functionality: In contrast to a virus, a worm does not passively wait for a user to spread it on a new system, but rather tries to actively penetrate new systems. Mostly it will hide itself in an inconspicuous place in the system with an inconspicuous name and change the target system so that the worm is called when the system starts. To do this, worms exploit security problems on the target system, such as a) Network serviceswho use standard passwords or no password at all,
b) Design and programming errorsin network services,
c) Design and programming errors in user programsthat use network services (e.g. e-mail clients). The worm could, for example, remotely control an e-mail application in order to distribute itself to all e-mail addresses entered there. Depending on the type of utility, the worm code can sometimes even execute itself on the target systems. In this case, no interaction with the user is necessary in order to spread from there.

4. Damage: The way a worm spreads means that it consumes a relatively large amount of network resources. This can lead to overloading or even failure of servers. Vulnerabilities in browsers and office applications are sometimes exploited on the day they become known. Modern Trojans are difficult to detect by virus scanners. In 2010, the Stuxnet worm was discovered that aimed to take control of WinCC, software from SIEMENS. This worm is characterized by a particularly high level of complexity, which is also reflected in the file size.
The economic damage caused by worms is greater than the damage caused by computer viruses. This is because viruses can only spread very slowly and are therefore often only spread locally.