RANSOM_ADAMLOCKER.THAOBFH

 Analysis by: Mio Fidel Villena

 ALIASES:

Trojan.Win32.Diztakun.bggy (KASPERSKY), Mal/StupCryp-A (SOPHOS_LITE), Trojan.Ransom.AdamLocker.A (BITDEFENDER)

 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 adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It encrypts files found in specific folders.

  TECHNICAL DETAILS

File Size:

669,184 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Feb 2018

Payload:

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

  • %ProgramData%\adm_64.exe

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
run = C:\run.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CLASSES_ROOT\.adam
{default} = adam

HKEY_CLASSES_ROOT\adam\shell\
open\command
{default} = {malware path and filename} %l

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = 1

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Software\Mircrosoft\
Windows\CurrentVersion\Policies\
Explorer
NoRun = 1

(Note: The default value data of the said registry entry is {user preference}.)

HKEY_CURRENT_USER\Software\Mircrosoft\
Windows\CurrentVersion\Policies\
Explorer
NoRightClick = 1

(Note: The default value data of the said registry entry is {user preference}.)

It adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

(Note: The default value data of the said registry entry is {user preference}.)

Propagation

This Ransomware drops the following copy(ies) of itself in all removable drives:

  • {removable drive letter}:\host_adm.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
shellexecute=host_adm.exe

Other Details

This Ransomware does the following:

  • Displays the following window (lockscreen) as ransom note:
  • This ransomware requires a key in order to decrypt the encrypted files. The key is "8jg7RPUMOvLBwr6WK6tf".
  • It displays the following after successfully entering the required key:

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • %User Profile%\Documents
  • %User Profile%\Pictures
  • %User Profile%\Downloads
  • %User Profile%\Desktop
  • D:\

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It renames encrypted files using the following names:

  • {original filename and extension}.adam

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.950.08

FIRST VSAPI PATTERN DATE:

06 Feb 2018

VSAPI OPR PATTERN File:

13.951.00

VSAPI OPR PATTERN Date:

07 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

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_CLASSES_ROOT\.adam
    • {default} = adam
  • In HKEY_CLASSES_ROOT\adam\shell\open\command
    • {default} = {malware path and filename} %l
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • run = C:\run.exe

Step 5

Restore this modified 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\Policies\Explorer
    • From: NoFolderOptions = 1"
      To: NoFolderOptions = {user preference}"
  • In HKEY_CURRENT_USER\Software\Mircrosoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoRun = 1"
      To: NoRun = {user preference}"
  • In HKEY_CURRENT_USER\Software\Mircrosoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoRightClick = 1"
      To: NoRightClick = {user preference}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System
    • From: DisableTaskMgr = 1"
      To: DisableTaskMgr = {user preference}"

Step 6

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.
  • %ProgramData%\adm_64.exe
  • {removable drive letter}:\host_adm.exe

Step 7

Search and delete AUTORUN.INF files created by RANSOM_ADAMLOCKER.THAOBFH that contain these strings

[ Learn More ]
[autorun]
shellexecute=host_adm.exe

Step 8

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


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