TROJ_CRYPLOCK.HSP

 Analysis by: Sammy Chua

 ALIASES:

Trojan:Win32/Dynamer!ac (Microsoft); Win32/Filecoder.DI (ESET-NOD32); Trojan.Win32.CryptoLocker.286720[h] (ViRobot)

 PLATFORM:

Windows

 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.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

286,720 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Apr 2015

Payload:

Connects to URLs/IPs, Encrypts files, Deletes files

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:

  • %All Users Profile%\Application Data\{random folder name}\01000000
  • %Windows%\{random 8 letters}.exe

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It drops the following non-malicious files:

  • %Desktop%\DECRYPT_INSTRUCTIONS.txt
  • %Desktop%\DECRYPT_INSTRUCTIONS.html
  • %All Users Profile%\Application Data\{random folder name}\00000000
  • %All Users Profile%\Application Data\{random folder name}\02000000
  • %All Users Profile%\Application Data\{random folder name}\03000000
  • %All Users Profile%\Application Data\{random folder name}\04000000
  • %All Users Profile%\Application Data\{random folder name}\05000000
  • %All Users Profile%\Application Data\{random folder name}\06000000

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in 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.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.)

It creates the following folders:

  • %All Users Profile%\Application Data\{random folder name}

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{random}

It injects codes into the following process(es):

  • created explorer.exe

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
{random 8 letters} = "%Windows%\{random 8 letters}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\
MyStdioFile

HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\
MyStdioFile\Recent File List

HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\
MyStdioFile\Settings

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
EnabledV8 = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
EnabledV9 = "0"

Information Theft

This Trojan gathers the following data:

  • Machine GUID
  • Computer name

Other Details

This Trojan connects to the following website to send and receive information:

  • https://{BLOCKED}er.ru/topic.php

It encrypts files with the following extensions:

  • avi
  • wav
  • mp3
  • gif
  • ico
  • png
  • bmp
  • txt
  • html

It renames encrypted files using the following names:

  • {original file name and extension}.encrypted

However, as of this writing, the said sites are inaccessible.

NOTES:

This Trojan drops the ransom notes DECRYPT_INSTRUCTIONS.html and DECRYPT_INSTRUCTIONS.txt to every folder it encrypts. It deletes shadow copies by executing the following command:

vssadmin.exe Delete Shadows /All /Quiet

It does not encrypt files with the following extensions:

  • bat
  • chm
  • cmd
  • dll
  • exe
  • ini
  • lnk
  • log
  • msi
  • scr
  • sys
  • tmp
  • url

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.632.03

FIRST VSAPI PATTERN DATE:

27 Apr 2015

VSAPI OPR PATTERN File:

11.633.00

VSAPI OPR PATTERN Date:

28 Apr 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_CRYPLOCK.HSP

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete the files detected as TROJ_CRYPLOCK.HSP

*Note: Some component files may be hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.

To stop the malware/grayware from running when certain files are opened:

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Right-click Start then click Search....
  2. In the File name* input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012 (R2):

  1. Open a Windows Explorer window.
    • For Windows Vista, 7, and Server 2008 users, click Start>Computer.
    • For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen,then click File Explorer.
  2. In the Search Computer/This PC input box, type the name of the file that was detected earlier.
  3. Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: Read the following Microsoft page if these steps do not work on Windows 7.

Step 6

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
    • {random 8 letters} = "%Windows%\{random 8 letters}.exe"

Step 7

Delete this registry key

[ 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\Pocal AppWizard-Generated Applications
    • HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\MyStdioFile
  • In HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\MyStdioFile\Recent File List
    • HKEY_CURRENT_USER\Software\Pocal AppWizard-Generated Applications\MyStdioFile\Settings

Step 8

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %All Users Profile%\Application Data\{random folder name}

Step 9

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • DECRYPT_INSTRUCTIONS.html
  • DECRYPT_INSTRUCTIONS.txt

Step 10

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_CRYPLOCK.HSP. 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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