Coming back, I want you to know that such a network of malware-infected computers are called Botnet. Below is an example of a Botnet that can serve multiple malicious purposes (sending spam or malware or a significant Gbps number for DoS) - Figure 4.6:
Figure 4.6
In addition to these network-related attacks, there are also attacks to "break" passwords:
1) Brute Force
2) Dictionary Attack
3) Rainbow table
1) Brute Force
Brute Force is a form of cyber attack that aims to gain unauthorized access to the system (a site administration server, server, network equipment, etc.). This technique uses "brute force," meaning the attacker tries to guess the password with a minimum of logic behind. Often, this technique leads to failure and waiver by the attacker, but there are many cases where access to the system is prevented because it has not changed its default password (which is often "admin" or "12345678")
2) Dictionary attack
A Dictionary Attack goes a little bit more targeted on the victims system because there are several external factors that relate to that organization / person.
With the help of some tools, hundreds or even thousands of words can be generated that can be tried to get access to the system. The disadvantage of this type of attack is that it can take a long time (depending on the number of words and the security of the system), and the dictionary does not guarantee the success of the attack.