Dropper Trojan leaks user data

May 30, 2014

The Dell Sonicwall Threats Research team has discovered an info stealer Trojan that leaks system information. It uses SSL to communicate with remote C&C servers. The malware analysed here appears to be a dropper Trojan that can download and run further malware.

Infection Cycle:

The Trojan uses the following icon to masquerade as a harmless PDF file:

The Trojan adds the following file to the filesystem:

  • %APPDATA%Microsoftqfmcommon.exe [Detected as GAV: Dapato.EBEE (Trojan)]
  • %APPDATA%2288127.bat (contains cleanup code to delete original executable)

The Trojan adds the following key to the Windows registry to enable startup after reboot:

  • HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun qfmcommon.exe "%APPDATA%Microsoftqfmcommon.exe"

Upon execution the Trojan injects code into a running instance of explorer.exe:

The injected code makes the following post request to a remote C&C server using SSL over port 8080:

The encrypted data that is sent contains the following data. It contains the session username and geographical information amongst other data:

The above request causes the C&C server to return a malicious executable:

The following C&C server IP addresses were discovered in the injected code. The Trojan tries each server until it receives a reply:

The Trojan continually cycles through the list of C&C servers and downloads an executable if the connection is successful. The executable downloaded can lead to malware from any family designated by the operators.

SonicWALL Gateway AntiVirus provides protection against this threat via the following signature:

  • GAV: Dapato.EBEE (Trojan)