Trojan-Downloader

Classification

Malware

Trojan-Downloader

W32

Trojan.downloader.variant, Trojan.downloader.js

Summary

This type of trojan secretly downloads malicious files from a remote server, then installs and executes the files.

Removal

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

Suspect a file is incorrectly detected (a False Positive)?

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest detection database updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    NOTE If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note You need administrative rights to change the settings.

Find out more

Knowledge Base

Find the latest advice in our Community Knowledge Base.

User Guide

See the user guide for your product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details

A trojan-downloader is a type of trojan that installs itself to the system and waits until an Internet connection becomes available to connect to a remote server or website in order to download additional programs (usually malware) onto the infected computer.

Installation

Attackers often distribute trojan-downloaders as part of the payload of another harmful program, such as a trojan-dropper, which silently drop and install the trojan-downloader on a device.

Trojan-downloaders are also commonly distributed as disguised file attached to spam emails. The attached programs are typically labelled using legitimate-sounding program or document names, such as 'invoice' or 'accounts.exe', as a simple form of social engineering. If the file attachment is opened, the trojan-downloader is installed.

Impact

Once a trojan-downloader has been installed on a machine, it will try to contact to a remove server or website, where it can either directly fetch additional files for download, or find further instructions from the attackers on where to find the files.

For representative examples of trojan-downloaders, please see the following descriptions: