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TROJ_CRYPTED.BLC

February 12, 2015
 Analysis by: David John Agni
 ALIASES:

Trojan.Win32.Crypt (Ikarus)

 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:

387,784 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Feb 2015

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 depending on the platform/operating system of the affected computer:

  • %Windows%\{Random Filename}.exe (Windows XP and Below)
  • %AppDataLocal%\{Random Filename}.exe (Windows Vista and Above)

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run (Winodws Vista and Above)
GoogleUpdate = "%AppDataLocal%\{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\CurrentControlSet\
Services\googleupdate (Windows XP and Below)
ImagePath = "%Windows%\{Random Filename}.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\googleupdate (Windows XP and Below)
DisplayName = "Google Update Service"

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}n.{BLOCKED}ip.com
  • {BLOCKED}.{BLOCKED}.239.151
  • {BLOCKED}b.{BLOCKED}2.no
  • {BLOCKED}l.{BLOCKED}k.de
  • {BLOCKED}po.{BLOCKED}o.com
  • {BLOCKED}s.{BLOCKED}d.i2p2.no
  • {BLOCKED}k.{BLOCKED}4.eu
  • {BLOCKED}.{BLOCKED}.206.176
  • {BLOCKED}.{BLOCKED}.52.146
  • {BLOCKED}.{BLOCKED}.3.218
  • {BLOCKED}.{BLOCKED}.11.124
  • {BLOCKED}.{BLOCKED}.131.92
  • {BLOCKED}.{BLOCKED}.175.138
  • {BLOCKED}.{BLOCKED}.43.254
  • {BLOCKED}.{BLOCKED}.215.219
  • {BLOCKED}.{BLOCKED}.91.58

It deletes the initially executed copy of itself