Downloader Trojan

Posted: April 12, 2024
from Cybersecurity Glossary
Downloader Trojan, Trojan-Downloader
Windows , macOS , Linux , Android , iOS
Trojan-Downloader.Win32, Trojan-Downloader.MSIL
Can install various types of malware without user's knowledge
Risk Level:
Very High!

Downloader trojans are malicious programs that disguise themselves as harmless files like software updates or games. Once executed, they connect to a remote server to download and install further malware, such as viruses, ransomware, or spyware, onto the infected system. They serve as a hidden doorway, enabling other malicious software to compromise the device.

Possible symptoms

  • Installation of additional malicious software
  • Corruption or encryption of files
  • Unauthorized modifications to system settings
  • Unexpected network activity from the device
  • Stealthy operations without user's consent

Sources of the infection

  • Compromised software updates
  • Infected game downloads
  • Malicious attachments in emails
  • Fake applications


Downloader trojans are a type of Trojan malware that disguise themselves as legitimate software to trick users into installing them. These trojans focus on downloading and executing additional malware onto the infected device, serving as a 'hidden doorway' for other malicious software such as viruses, ransomware, or spyware to enter and infect the system. Once installed, they engage in various malicious activities such as corrupting files, encrypting files to demand ransom payments, or capturing keystrokes.

The most common sources of downloader trojans include compromised software updates, infected game downloads, malicious email attachments, and fake applications. These trojans target multiple platforms including Windows, macOS, Linux, Android, and iOS, making them a significant threat to a wide range of devices.

The presence of downloader trojans on a device can be indicated by symptoms such as the installation of unknown software, corruption or encryption of files, unauthorized changes to system settings, unexpected network activity, and operations that occur without the user's consent, aiming to remain undetected.

To combat the threat of downloader trojans, it is crucial to maintain up-to-date security software, avoid opening suspicious email attachments, download files and software only from trusted sources, and exercise caution when browsing the internet to prevent accidental downloads of malicious software.

🤔 What to do?

If your device is infected with a downloader trojan, take the following steps:

  1. Isolate the device to prevent further spread of malware.
  2. Run a thorough Anti-Malware scan to identify and remove the malware.
  3. Review and clean up system settings and files that were modified.
  4. Restore affected files from backup if possible.
  5. Update your security measures to prevent future infections.

🛡️ Prevention

To prevent downloader trojan infections, follow these steps:

  1. Use reliable security software and keep it updated.
  2. Avoid opening suspicious email attachments.
  3. Only download software and files from trusted sources.
  4. Exercise caution when browsing, and avoid malicious websites.

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