RANSOM_FAKELOCKY.A

September 19, 2017
 Analysis by: Oliver Ramirez
 ALIASES:

Win32/Filecoder.ArmaLocky.A trojan (NOD32);

 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

This Ransomware encrypts files found in specific folders. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

252,416 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

02 Sep 2017

Payload:

Displays windows, Encrypts files

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
locky = {malware path}

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CLASSES_ROOT\.armadilo1\shell\
Open with Internet Explorer\command

HKEY_CLASSES_ROOT\.armadilo1

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = 1

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\srservice
Start = "0x00000004"

(Note: The default value data of the said registry entry is "0x00000002".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\swprv
Start = "0x00000004"

(Note: The default value data of the said registry entry is "0x00000003".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\vss
Start = "0x00000004"

(Note: The default value data of the said registry entry is "0x00000003".)

Dropping Routine

This Ransomware drops the following files:

  • %Desktop%\install.log

(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.)

Ransomware Routine

This Ransomware encrypts files found in the following folders:

  • {Drive Letter}:\

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

  • .exe
  • .dll

It avoids encrypting files with the following strings in their file path:

  • %System Root%\windows
  • %System Root%\boot
  • %System Root%\msocache
  • %System Root%\config.msi

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

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

  • .armadilo1

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

  • {folder of encrypted files}\_ReadMe_,txt
  • %Desktop%\_Locky_HELP_.html

(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.)

NOTES:

This ransomware executes the following commands as part of its preparation for encrypting files:

  • -vssadmin delete shadows /for={drive letter} /all /quiet
  • -schtasks /Change /TN Microsoft\Windows\SystemRestore\SR /Disable
  • -sc config swprv start= disabled
  • -sc config vss start= disabled
  • -sc stop vss
  • -Reg add HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore /v DisableSR /t REG_DWORD /d 1 /f
  • -sc config srservice start= disabled
  • -net stop srservice

The ransom note file %Desktop%\_Locky_HELP_.html contains:

The ransom note file {folder of encrypted files}\_ReadMe_,txt contains:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.652.08

FIRST VSAPI PATTERN DATE:

11 Sep 2017

VSAPI OPR PATTERN File:

13.653.00

VSAPI OPR PATTERN Date:

12 Sep 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

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_CLASSES_ROOT\.armadilo1

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
    • locky = {malware path}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
    • DisableSR = "1"

Step 5

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\srservice
    • From: Start = "0x00000004"
      To: Start = "0x00000002"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\swprv
    • From: Start = "0x00000004"
      To: Start = "0x00000003"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\vss
    • From: Start = "0x00000004"
      To: Start = "0x00000003"

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.
  • {folder of encrypted files}\_ReadMe_,txt
  • %Desktop%\_Locky_HELP_.html

Step 7

Scan your computer with your Trend Micro product to delete files detected as RANSOM_FAKELOCKY.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 this Knowledge Base page for more information.

Step 8

Restore encrypted files from backup.


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