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RANSOM_JOBCRYPTER.B

February 24, 2017
 Analysis by: Marvelous Pelin
 ALIASES:

Ransom.JobCrypter(Symantec); Ransom.JobCrypter(Malwarebytes)

 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.

  TECHNICAL DETAILS

File Size:

408,064 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Feb 2017

Payload:

Connects to URLs/IPs, Encrypts files, Renames 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 and executes them:

  • %Application Data%\L o c k e r.exe - set attributes to Hidden

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 drops the following files:

  • %User Temp%\Screen.jpg - screenshot

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

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
application = %Application Data%\L o c k e r.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software
Code = {random value}

HKEY_CURRENT_USER\Software
1 = 1

Other Details

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

  • {BLOCKED}.{BLOCKED}.1and1.fr:587

It renames encrypted files using the following names:

  • {original filename and extension}.css

It does the following:

  • Avoids encrypting files with the following strings in their filepath:
    • windows\
    • Progam Files
  • Avoids encrypting files with the following filename:
    • autoexec.bat
    • boot.ini
    • Bootfont.bin
    • config.sys
    • desktop.ini
    • Google Chrome.lnk
    • Internet Explorer.lnk
    • io.sys
    • Mozilla Firefox.lnk
    • MSDOS.sys
    • NTDETECT.COM
    • pagefile.sys

NOTES:

This ransomware appends the following strings to the encrypted files which serves as its ransom note:

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

13.222.00

FIRST VSAPI PATTERN DATE:

14 Feb 2017

VSAPI OPR PATTERN File:

13.223.00

VSAPI OPR PATTERN Date:

15 Feb 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

Restart in Safe Mode

[ Learn More ]

Step 4

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
    • application = %Application Data%\L o c k e r.exe
  • In HKEY_CURRENT_USER\Software
    • Code = {random value}
  • In HKEY_CURRENT_USER\Software
    • 1 = 1

Step 5

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.
  • %User Temp%\Screen.jpg

Step 6

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

Step 7

Restore encrypted files from backup.


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