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TROJ_CRILOCK.YMO

May 19, 2014
 Modified by: RonJay Kristoffer Caragay
 ALIASES:

Trojan:Win32/Crilock (Microsoft); Trojan-Ransom.Win32.Blocker.enwh(Kasperksy); Trojan.Cryptolocker(Norton); Trojan.Win32.Crilock(Ikarus)

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

815,104 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 May 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:

  • %AppDataLocal%\{random filename}.exe

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local 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 = "%AppDataLocal%\{random filename}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
*CryptoLocker = "%AppDataLocal%\{random filename}.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\CryptoLocker_0388
VersionInfo = "{hex values}"

HKEY_CURRENT_USER\Software\CryptoLocker_0388
PublicKey = "{hex values}"

HKEY_CURRENT_USER\Software\CryptoLocker_0388
Wallpaper = "{hex values}"

HKEY_CURRENT_USER\Software\CryptoLocker_0388\
Files
{path and filename of encrypted files} = "{hex values}"

HKEY_CLASSES_ROOT\{random characters}\shell\
open\command
(Default) = ""%AppDataLocal%\{random filename.exe}" - "%1" %*"

HKEY_CURRENT_USER\Software\Classes\
{random characters}\shell\open\
command
(Default) = ""%AppDataLocal%\{random filename.exe}" - "%1" %*"

Dropping Routine

This Trojan drops the following files:

  • %Desktop%\{random filename}.bmp

(Note: %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.)

Other Details

This Trojan connects to the following possibly malicious URL:

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

It deletes itself after execution.