Malicious software
Malicious software (also called "malware") includes:
- viruses
- trojans
Viruses
Viruses are small programs that "infect" other programs by inserting themselves inside them. When the infected program runs, so does the virus, which allows it to perform it tasks. One of the tasks a virus does is to copy itself from one infected program to another program. This allows it to spread to many programs on the machine and gives it more chances to run. The user will be unaware that any software has been loaded on their machine. Typical source of viruses include:
- Infected files from CDs, USBs and other removable media
- Infected downloads
- Infected email attachments
Trojans
Trojans are programs that perform a desirable function e.g. a free game or utility, but also perform some additional malicious task. A trojan is not an infected program - this was the primary purpose of the program. A common source of trojans are websites that offer free software or offer to fix a problem.
Malware threats
Malware can do one or more of these:
- Record all keystrokes including:
- passwords
- credit card details
- emails written
- Search files for personal data
- Encrypt the hard drive and hold it to ransom
- Allow the machine to be remote controlled
- Send spam emails