Analysis by: Cris Nowell Pantanilla

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware

This malware is one of the variants/components of RETADUP malware discovered on September 2017 to be hitting users in South America for purposes of cryptocurrency mining. Users infected by this malware may find malicous behaviors being exhibited upon their system.

This Worm may be dropped by other malware.

It is a component of other malware.

  TECHNICAL DETAILS

File Size:

3,856 bytes

File Type:

AU3

Memory Resident:

No

Initial Samples Received Date:

13 Jul 2017

Payload:

Creates files

Arrival Details

This Worm may be dropped by the following malware:

Installation

This Worm creates the following folders:

  • {Drive}:\AntiUsbShortCut

It is a component of other malware.

Other System Modifications

This Worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
CpuOptimizer = "C:\newcpuspeed\Cpufix.exe "C:\newcpuspeed\cpuage.tnt""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Checkcpu = "C:\Windows\system32\cmd.exe /c start C:\newcpuspeed\Cpufix.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
CpuOptimizer = "C:\newcpuspeed\Cpufix.exe "C:\newcpuspeed\cpuage.tnt""

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
Checkcpu = "C:\Windows\system32\cmd.exe /c start C:\newcpuspeed\Cpufix.exe"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

(Note: The default value data of the said registry entry is 1.)

Other Details

This Worm does the following:

  • This is a malicious AutoIt script (AU3) used by other malware for its routines. It requires its component files to execute properly.

NOTES:

This worm drops the following files on removable drives:

  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AntiShortCut.lnk
  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AntiUsb.exe
  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AntiUsbShortCut.zip
  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AntiUsbShortCut.lnk
  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AntiUsbWorm.zip
  • {Drive}:\AntiUsbShortCut\AntiUsbShortCut\AutoIt3.exe
  • {Drive}:\{folder}\Downloads.lnk

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.530.02

FIRST VSAPI PATTERN DATE:

13 Jul 2017

VSAPI OPR PATTERN File:

13.531.00

VSAPI OPR PATTERN Date:

14 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

Remove the malware/grayware file dropped/downloaded by WORM_RETADUP.D. (Note: Please skip this step if the threat(s) listed below have already been removed.)

Step 3

Identify and terminate files detected as WORM_RETADUP.D

[ 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

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
    • CpuOptimizer = "C:\newcpuspeed\Cpufix.exe "C:\newcpuspeed\cpuage.tnt""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Checkcpu = "C:\Windows\system32\cmd.exe /c start C:\newcpuspeed\Cpufix.exe"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • CpuOptimizer = "C:\newcpuspeed\Cpufix.exe "C:\newcpuspeed\cpuage.tnt""
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • Checkcpu = "C:\Windows\system32\cmd.exe /c start C:\newcpuspeed\Cpufix.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\Explorer\Advanced
    • From: ShowSuperHidden = 0
      To: ShowSuperHidden = 1

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. {Drive}:\AntiUsbShortCut\

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_RETADUP.D. 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.


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