RANSOM_CHIYUNLONG.A

 Analysis by: Marcus Ma. Antonio Capistrano

 ALIASES:

Ransom.Enciphered (NORTON), Ransom:Win32/Genasom (MICROSOFT), TR/Agent.gkqln (ANTIVIR)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It employs registry shell spawning by adding certain registry entries. This allows this malware to execute even when other applications are opened.

  TECHNICAL DETAILS

File Size:

1,327,104 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Jul 2017

Payload:

Displays graphics/image, Displays windows, Encrypts files

Arrival Details

This Ransomware 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 Ransomware drops the following files:

  • %Desktop%\bmp.bmp
  • %Desktop%\ico.ico
  • %System Root%\yl.ini
  • %Program Files%\Resurrection
  • %System Root%\Second Resurrection.exe
  • %Program Files%\Second Resurrection
  • %Program Files%\China Yun Long

(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.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It drops and executes the following files:

  • %Windows%\Resurrection.exe
  • %Desktop%\China Yun Long.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Resurrection.exe = %Windows%\Resurrection.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Malware file name} = {Malware file path}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
China Yun Long.exe = %Desktop%\China Yun Long.exe

It employs registry shell spawning to ensure its execution when certain file types are accessed by adding the following entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
yl\Shell\Open\
Command
{blank} = "%Desktop%\China Yun Long.exe" "%1"

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
yl
EditFlags = 2

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.yl
{blank} = yl

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %Desktop%\bmp.bmp

Other Details

This Ransomware encrypts files with the following extensions:

  • .doc
  • .jpg
  • .png
  • .pdf
  • .docx
  • .wps
  • .xlsx
  • .xls
  • .txt
  • .excel
  • .word
  • .et
  • .ppt
  • .dps
  • .rar
  • .zip
  • .7z
  • .h
  • .bak
  • .e
  • .html
  • .htm
  • .asp
  • .php
  • .mp3
  • .mp4
  • .avi

It does the following:

  • Upon execution of the malware, the user is presented with the following window:
  • Files with .yl extension (encrypted files) share the icon of the malware by modifying the following registry entries:
    • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\yl\DefaultIcon
    • {blank} = %Desktop%\China Yun Long.exe,0

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

  • .yl

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.544.04

FIRST VSAPI PATTERN DATE:

20 Jul 2017

VSAPI OPR PATTERN File:

13.545.00

VSAPI OPR PATTERN Date:

21 Jul 2017

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

Identify and terminate files detected as RANSOM_CHIYUNLONG.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 4

Terminate this process using Process Explorer

[ Learn More ]
If you still cannot terminate the malware/grayware process because it is not displayed in Process Explorer, please restart your computer in Safe Mode. You may refer to this page for details.

Step 5

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.

  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\yl
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.yl

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
    • Resurrection.exe = %Windows%\Resurrection.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Malware file name} = {Malware file path}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • China Yun Long.exe = %Desktop%\China Yun Long.exe

Step 7

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.  
  • %Windows%\Resurrection.exe
  • %Desktop%\China Yun Long.exe
  • %Desktop%\bmp.bmp
  • %Desktop%\ico.ico
  • %System Root%\yl.ini
  • %Program Files%\Resurrection
  • %System Root%\Second Resurrection.exe
  • %Program Files%\Second Resurrection
  • %Program Files%\China Yun Long

Step 8

Scan your computer with your Trend Micro product to delete files detected as RANSOM_CHIYUNLONG.A. 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 the following Trend Micro Support pages for more information:

Step 9

Reset your Desktop properties

[ Learn More ]

Step 10

Restore encrypted files from backup.


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