Overview of Malware
Now that you know about the tools that hacker use, this topic introduces you to different types of malware that hackers use to gain access to end devices.
End devices are particularly prone to malware attacks. It is important to know about malware because threat actors rely on users to install malware to help exploit the security gaps.
Viruses and Trojan Horses
The first and most common type of computer malware is a virus. Viruses require human action to propagate and infect other computers. For example, a virus can infect a computer when a victim opens an email attachment, opens a file on a USB drive, or downloads a file.
The virus hides by attaching itself to computer code, software, or documents on the computer. When opened, the virus executes and infects the computer.
- Alter, corrupt, delete files, or erase entire drives.
- Cause computer booting issues, and corrupt applications.
- Capture and send sensitive information to threat actors.
- Access and use email accounts to spread.
- Lay dormant until summoned by the threat actor.
Modern viruses are developed for specific intent such as those listed in the table.
|Types of Viruses||Description|
|Boot sector virus||Virus attacks the boot sector, file partition table, or file system.|
|Firmware virus||Virus attacks the device firmware.|
|Macro virus||Virus uses the MS Office or other applications macro feature maliciously.|
|Program virus||Virus inserts itself in another executable program.|
|Script virus||Virus attacks the OS interpreter which is used to execute scripts.|
Threat actors use Trojan horses to compromise hosts. A Trojan horse is a program that looks useful but also carries malicious code. Trojan horses are often provided with free online programs such as computer games. Unsuspecting users download and install the game, along with the Trojan horse.
There are several types of Trojan horses as described in the table.
|Type of Trojan Horse||Description|
|Remote-access||Trojan horse enables unauthorized remote access.|
|Data-sending||Trojan horse provides the threat actor with sensitive data, such as passwords.|
|Destructive||Trojan horse corrupts or deletes files.|
|Proxy||Trojan horse will use the victim’s computer as the source device to launch attacks and perform other illegal activities.|
|FTP||Trojan horse enables unauthorized file transfer services on end devices.|
|Security software disabler||Trojan horse stops antivirus programs or firewalls from functioning.|
|Denial of Service (DoS)||Trojan horse slows or halts network activity.|
|Keylogger||Trojan horse actively attempts to steal confidential information, such as credit card numbers, by recording key strokes entered into a web form.|
Viruses and Trojan horses are only two types of malware that threat actors use. There are many other types of malware that have been designed for specific purposes.
Other Types of Malware
The table shows details about many different types of malware.