Analysis by: Ryan Gardo
ALIASES:

Trojan.Win32.Staser.tdv(Kaspersky); RDN/Generic.dx!d2d( McAfee); DDoS:Win32/Nitol.A(Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 39,424 bytes
File Type: EXE
Initial Samples Received Date: 13 Aug 2014

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System%\{random filename}.exe
  • %User Temp%\SOFTWARE.LOG

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %System%\hra33.dll

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Distribuemf
DisplayName data = Distribubcl Transaction Coordinator Service

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Distribuemf
ImagePath = %System%\{random filename}.exe

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Distribuemf

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

This worm drops lpk.dll file in all folders in all physical and removable drives containing an .EXE file.