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Downloader trojan

(also downloader, trojan-downloader)

Downloader trojan definition

A downloader trojan is a type of malware designed to install malicious software or files onto a victim’s device (e.g., smartphone or computer) without them knowing. A trojan is malware that disguises itself as legitimate or useful software. Downloader trojans focus on downloading and executing additional malware onto the infected system. It becomes a “hidden doorway” that allows other viruses, ransomware, or spyware to infect the device.

See also: banker trojan, trojan

How downloader trojans infect devices

  • The attacker makes a downloader trojan available for an unsuspecting user to download. The trojan disguises itself as a harmless or legitimate file, such as a software update or a game.
  • The user downloads and runs it on their device without knowing it’s malicious.
  • Once the downloader trojan is installed, it starts its malicious activities in the background.
  • The downloader trojan establishes a connection with a remote server controlled by the attacker. The server contains additional malware the trojan aims to download and install.
  • The trojan gets instructions from the remote server to download specific malware payloads (e.g., viruses, ransomware, or spyware).
  • The trojan installs the downloaded malware onto the victim’s device without the user’s awareness.
  • Once the malware is installed, it carries out various malicious activities (like corrupting files, encrypting files to demand payment, or seeing what the user types).
  • Downloader trojans attempt to remain undetected by hiding their processes, modifying system files, or evading security software.

How to prevent downloader trojans

  • Use reliable security software.
  • Don’t open suspicious email attachments.
  • Download software and files from reliable sources only.
  • Be cautious when visiting websites: some may be malicious.