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RANSOM_CRYPTOR.R038C0DBB18

March 06, 2018
 Analysis by: Marcus Ma. Antonio Capistrano
 ALIASES:

Trojan-Ransom.Win32.Cryptor.bqk (KASPERSKY), Trojan:Win32/Occamy.B (MICROSOFT), W32/Filecoder.NOZ!tr (FORTINET)

 PLATFORM:

Windows

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

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: No

  • 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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

It is capable of encrypting files in the affected system.

It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

914,432 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Feb 2018

Payload:

Terminates processes, Displays message/message boxes, 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 a copy of itself in the following folders using different file names:

  • %Application Data%\info.exe

(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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

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

  • BleepingComputer_rapid

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
Encrypter_074 = %Application Data%\info.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
userinfo = %Application Data%\recovery.txt

The scheduled task executes the malware at the following period:

  • Every minute
  • Upon login

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\EncryptKeys
local_enc_private_key_len = {random data}

HKEY_CURRENT_USER\Software\EncryptKeys
local_enc_private_key = {random data}

HKEY_CURRENT_USER\Software\EncryptKeys
local_public_key_len = {random data}

HKEY_CURRENT_USER\Software\EncryptKeys
local_public_key = {random data}

Process Termination

This Ransomware terminates the following processes if found running in the affected system's memory:

  • msftesql.exe
  • sqlagent.exe
  • sqlbrowser.exe
  • sqlservr.exe
  • sqlwriter.exe
  • oracle.exe
  • ocssd.exe
  • dbsnmp.exe
  • synctime.exe
  • mydesktopqos.exe
  • agntsvc.exeisqlplussvc.exe
  • xfssvccon.exe
  • mydesktopservice.exe
  • ocautoupds.exe
  • agntsvc.exeagntsvc.exe
  • agntsvc.exeencsvc.exe
  • firefoxconfig.exe
  • tbirdconfig.exe
  • ocomm.exe
  • mysqld.exe
  • mysqld-nt.exe
  • mysqld-opt.exe
  • dbeng50.exe
  • sqbcoreservice.exe
  • excel.exe
  • infopath.exe
  • msaccess.exe
  • mspub.exe
  • onenote.exe
  • outlook.exe
  • powerpnt.exe
  • steam.exe
  • thebat.exe
  • thebat64.exe
  • thunderbird.exe
  • visio.exe
  • winword.exe
  • wordpad.exe
  • taskmgr.exe

Other Details

This Ransomware does the following:

  • It deletes all shadow copies by executing the following commands:
    • /c vssadmin.exe Delete Shadows /All /Quiet
    • /c wmic SHADOWCOPY DELETE
  • It disables Windows Startup Repair by executing the following command:
    • /c bcdedit.exe /set {default} recoveryenabled No
  • After its encryption routine, it opens the dropped ransom note:
  • If it detects AV software running in memory, the malware exits.
  • It disables or turns off Windows Error Recovery Screen on Startup using the following command:
    • /c bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
  • It deletes one or more system state backups by executing the following command:
    • /c wbadmin DELETE SYSTEMSTATEBACKUP

It is capable of encrypting files in the affected system.

It checks for the presence of the following antivirus and security applications:

  • AVP.EXE
  • ekrn.exe
  • avgnt.exe
  • ashDisp.exe
  • NortonAntiBot.exe
  • Mcshield.exe
  • avengine.exe
  • cmdagent.exe
  • smc.exe
  • persfw.exe
  • pccpfw.exe
  • fsguiexe.exe
  • cfp.exe
  • msmpeng.exe

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • How Recovery Files.txt
  • info.exe
  • recovery.txt

It avoids encrypting files found in the following folders:

  • Windows
  • intel
  • nvidia
  • ProgramData
  • temp

It appends the following extension to the file name of the encrypted files:

  • .rapid

It drops the following file(s) as ransom note:

  • %Application Data%\recovery.txt
  • {encrypted files directory}\How Recovery Files.txt

(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.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.960.04

FIRST VSAPI PATTERN DATE:

11 Feb 2018

VSAPI OPR PATTERN File:

13.961.00

VSAPI OPR PATTERN Date:

12 Feb 2018

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

To delete the added Scheduled Task:

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

  1. Click on Start>Programs>Accessories>System Tools>Scheduled Tasks
  2. Double-click on a job file.
  3. Check if the malware path and file name is in the Run: box.
  4. If it does, delete the job file.
  5. Repeat step 2-4 for the remaining job files.

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

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower-left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, select a Task.
  4. Check if the selected task starts the malware automatically. To do this, check the value in the Details column under the Actions tab in the lower-middle panel.
  5. If the malware path and file name is found, press DELETE and click Yes to delete the task.
  6. Repeat steps 3-5 for the remaining tasks.

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.

  • In HKEY_CURRENT_USER\Software
    • EncryptKeys

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
    • Encrypter_074 = %Application Data%\info.exe
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • userinfo = %Application Data%\recovery.txt

Step 7

Search and delete these files

[ 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.
  • %Application Data%\info.exe
  • %Application Data%\recovery.txt
  • {encrypted files directory}\How Recovery Files.txt

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_CRYPTOR.R038C0DBB18. 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 9

Restore encrypted files from backup.

NOTES:

  1. Run cmd.exe as administrator.
  2. To enable Windows Error Recovery Screen on Startup, use the following command:

    bcdedit /set {default} bootstatuspolicy displayallfailures

  3. To enable Startup Repair, use the following command:

    bcdedit /set {default} recoveryenabled Yes


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