Threat Description

Trojan-Downloader:​W32/Small.COY

Details

Aliases:Trojan-Downloader:​W32/Small.COY, Trojan-Downloader:​W32/Small.COY, Trojan-Downloader.Win32.Small.coy
Category:Malware
Type:Trojan-Downloader
Platform:W32

Summary



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



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

You may wish to refer to the Support Community for further assistance. You also may also refer to General Removal Instructions for a general guide on alternative disinfection actions.



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 e-mails 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 (e-mail) account login names and passwords
  • HTTP e-mail 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.






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