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TROJ_RANSOM.IGY

September 07, 2013
 ALIASES:

Trojan:Win32/Ransom.KW (Microsoft); Trojan-Ransom.Win32.Agent.pes (Kaspersky); Troj/Ransom-LA (Sophos)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan may arrive bundled with malware packages as a malware component. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

128512 bytes

File Type:

, EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Jul 2013

Arrival Details

This Trojan may arrive bundled with malware packages as a malware component.

It 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 files:

  • %System Root%\ProgramData\svcfnmainstvestvs\stppthmainfv.dll
  • %System Root%\how to decrypt files.lnk

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\{random number}
  • %System Root%\ProgramData
  • %System Root%\ProgramData\{random number}
  • %System Root%\ProgramData\svcfnmainstvestvs
  • %System Root%\ProgramData\svtstcrs

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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\CurrentControlSet\
Services\WinSamSs
ImagePath = {malware path and filename}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSamSs
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSamSs
DisplayName = "Windows Security Accounts Manager"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinSamSs
Description = "The startup of this service signals to other services that the Security Accounts Manager (SAM) is ready to accept other requests. Disabling this service will prevent other services in the system from being notified when the SAM is ready, which may in turn cause those services to fail to start correctly. This service should not be disabled."

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
svchost = "%System Root%\{random number}\svchost.exe"