Trojan-Downloader:W32/Small.COY

Classification

Malware

Trojan-Downloader

W32

Trojan-Downloader:W32/Small.COY, Trojan-Downloader:W32/Small.COY, Trojan-Downloader.Win32.Small.coy

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

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User Guide

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

Trojan-Downloader:W32/Small.COY belongs to a family of known primitive trojan downloaders that have a download URL encrypted in the end of their files. The URL to this particular trojan downloader (smsender.exe file) was spammed in emails to a large number of addresses.

Execution

When downloaded and run by a recipient, the trojan-downloader attempts to download and activate a file named installer2.0.26.exe from a website hosted in Canada.

The downloaded file is detected as 'Trojan-PSW.Win32.Agent.fy' and it is technically a trojan dropper. Once activated, it drops a DLL file and registers it as a component of Internet Explorer. This DLL file is the main spying component and it is activated when Internet Explorer is run. The spying component collects and sends out the following data:

  • Data from webforms that a user fills in including the URLs of the site
  • POP and SMTP (email) account login names and passwords
  • HTTP email account login names and passwords
  • MSN passwords
  • Outlook account information
  • Internet Explorer passwords for protected sites
  • IE autocomplete fields data
  • Information about an infected computer
  • Windows cached passwords

The trojan can also create a batch file that deletes system files from the Program Files and System Root (main Windows directory) folders.