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TROJ_CRILOCK.AA

September 22, 2013
 Analysis by: Joie Salvio
 ALIASES:

Trojan:Win32/Crilock.A (Microsoft), Win32/Filecoder.BQ trojan (ESET)

 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:

  • 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.

  TECHNICAL DETAILS

File Size:

708,608 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

18 Sep 2013

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 and executes them:

  • %Application Data%\{random GUID}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
CryptoLocker = "%Application Data%\{random GUID}.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • {pseudo random domain}.biz
  • {pseudo random domain}.ru
  • {pseudo random domain}.net
  • {pseudo random domain}.info
  • {pseudo random domain}.co.uk
  • {pseudo random domain}.com
  • {pseudo random domain}.org