Analysis by: Joie Salvio
 Modified by: Alvin Bacani
ALIASES:

Trojan:Win32/Crilock.A (Microsoft), Trojan-Ransom.Win32.Blocker.cgmz (Kaspersky)

 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

Infection Channel: Downloaded from the Internet

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: 670,720 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Sep 2013
Payload: Connects to URLs/IPs

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"

NOTES:

This Trojan connects to the following URLs to download the key used in encrypting the files:

  • {BLOCKED}ixcyosb.org
  • {BLOCKED}asjkp.net

It also connects to random generated IP addresses with the following extensions:

  • biz
  • co.uk
  • com
  • info
  • net
  • org
  • ru

It encrypts files with the following extensions:

  • *.3fr
  • *.accdb
  • *.arw
  • *.bay
  • *.cdr
  • *.cer
  • *.cr2
  • *.crt
  • *.crw
  • *.dbf
  • *.dcr
  • *.der
  • *.dng
  • *.doc
  • *.docm
  • *.docx
  • *.dwg
  • *.dxf
  • *.dxg
  • *.eps
  • *.erf
  • *.indd
  • *.kdc
  • *.mdb
  • *.mdf
  • *.mef
  • *.mrw
  • *.nef
  • *.nrw
  • *.odb
  • *.odc
  • *.odm
  • *.odp
  • *.ods
  • *.odt
  • *.orf
  • *.p12
  • *.p7b
  • *.p7c
  • *.pdd
  • *.pef
  • *.pem
  • *.pfx
  • *.ppt
  • *.pptm
  • *.pptx
  • *.psd
  • *.pst
  • *.ptx
  • *.r3d
  • *.raf
  • *.raw
  • *.rtf
  • *.rw2
  • *.rwl
  • *.sr2
  • *.srf
  • *.srw
  • *.wb2
  • *.wpd
  • *.wps
  • *.x3f
  • *.xlk
  • *.xls
  • *.xlsb
  • *.xlsm
  • *.xlsx

It demands users to pay a fine via any of the following payment methods:

  • Bitcoin
  • cashU
  • MoneyPak
  • Ukash

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.278.01
FIRST VSAPI PATTERN DATE: 12 Sep 2013
VSAPI OPR PATTERN File: 10.279.00
VSAPI OPR PATTERN Date: 12 Sep 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

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

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRILOCK.NIL. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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