Malware is a Malicious Software program which will harm the computer/system or want to do other actions without the knowledge of the owner consent. Malware may contain Viruses, Worms, Trojan Horses, and Spyware. It grouped and works together.
Cybercriminals may try to trap you into downloading some software or application referring to protect your computer by installing their security applications. This is called rogue(fake) security software. If you downloaded and installed into your system, cybercriminals may hack your system and steal your password or any other valuable information. This will happen with the help of malicious code. Malicious code may lie in the computer without your knowledge and continue their task silently.