Analysis by: Marvelous Pelin

 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: Dropped by other malware, Downloaded from the Internet

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.

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

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 231,424 bytes
File Type: DOC
Memory Resident: Yes
Initial Samples Received Date: 03 Mar 2017
Payload: Connects to URLs/IPs

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 drops the following files:

  • %ProgramData%\Windows:kernel32.{vbs or dll} - contains code to execute the data in
    HKEY_CURRENT_USER\Software\Microsoft\Windows
    Part = {mentioned in Other System Modification}

(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.)

It adds the following processes:

  • powershell.exe
  • nslookup.exe

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:

  • SourceFireSux

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
kernel32 = wscript %ProgramData%\Windows:kernel32.{vbs or dll}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
kernel32 = wscript %ProgramData%\Windows:kernel32.{vbs or dll}

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows
kernel32 = {base64 encoded values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows
Part = {code used to decode and execute data of the base64 values}

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}in.com/raw/sxPYz7fT

It does the following:

  • It randomly connects to one of the following domains to send and receive information:
    • {BLOCKED}w.me
    • {BLOCKED}d.pw
    • {BLOCKED}e.pw
    • {BLOCKED}h.pw
    • {BLOCKED}h.pw
    • {BLOCKED}d.me
    • {BLOCKED}x.pw
    • {BLOCKED}x.pw
    • {BLOCKED}f.pw
    • {BLOCKED}d.mo
    • {BLOCKED}o.pw
    • {BLOCKED}d.com
    • {BLOCKED}f.pw
    • {BLOCKED}f.pw
    • {BLOCKED}d.com
    • {BLOCKED}u.pw
    • {BLOCKED}u.pw
    • {BLOCKED}c.pw
    • {BLOCKED}s.pw
    • {BLOCKED}s.pw
    • {BLOCKED}e.pw
    • {BLOCKED}o.pw
    • {BLOCKED}p.pw
    • {BLOCKED}p.pw
    • {BLOCKED}f.pw
    • {BLOCKED}f.pw
    • {BLOCKED}t.pw
    • {BLOCKED}t.pw
    • {BLOCKED}t.pw
    • {BLOCKED}t.pw
    • {BLOCKED}e.pw
    • {BLOCKED}o.pw
    • {BLOCKED}g.pw
    • {BLOCKED}g.pw
    • {BLOCKED}q.pw
    • {BLOCKED}q.pw
    • {BLOCKED}r.pw
    • {BLOCKED}r.pw
    • {BLOCKED}f.pw
    • {BLOCKED}f.pw
    • {BLOCKED}q.pw
    • {BLOCKED}q.pw
    • {BLOCKED}w.my
    • {BLOCKED}d.pw
    • {BLOCKED}f.pw
    • {BLOCKED}d.pw
    • {BLOCKED}d.pw
    • {BLOCKED}m.pw
    • {BLOCKED}m.pw
    • {BLOCKED}j.pw
    • {BLOCKED}j.pw
    • {BLOCKED}c.pw
    • {BLOCKED}c.pw
    • {BLOCKED}t.pw
    • {BLOCKED}t.pw
    • {BLOCKED}u.pw
    • {BLOCKED}u.pw
    • {BLOCKED}o.pw
    • {BLOCKED}o.pw
    • {BLOCKED}m.pw
    • {BLOCKED}m.pw
    • {BLOCKED}s.pw
    • {BLOCKED}s.pw
    • {BLOCKED}p.pw
    • {BLOCKED}p.pw
    • {BLOCKED}a.pw
    • {BLOCKED}o.pw
    • {BLOCKED}y.pw
    • {BLOCKED}y.pw
    • {BLOCKED}c.pw
    • {BLOCKED}d.pw
    • {BLOCKED}d.pw
    • {BLOCKED}d.pw
    • {BLOCKED}q.pw
    • {BLOCKED}q.pw
    • {BLOCKED}d.pw
    • {BLOCKED}x.pw
    • {BLOCKED}x.pw
    • {BLOCKED}p.pw
    • {BLOCKED}p.pw
    • {BLOCKED}z.pw
    • {BLOCKED}z.pw
  • It uses the Windows Task Scheduler to add this scheduled task:
    • kernel32 = %ProgramData%\Windows:kernel32.{dll or vbs}
      executed when the computer is on idle after 30 minutes

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.254.05
FIRST VSAPI PATTERN DATE: 03 Mar 2017
VSAPI OPR PATTERN File: 13.255.00
VSAPI OPR PATTERN Date: 04 Mar 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

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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • kernel32 = wscript %ProgramData%\Windows:kernel32.{vbs or dll}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • kernel32 = wscript %ProgramData%\Windows:kernel32.{vbs or dll}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • kernel32 = {base64 encoded values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • Part = {code used to decode and execute data of the base64 values}

Step 5

Deleting Scheduled Tasks

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

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each task that has the following value in the Schedule column:
    • kernel32 = %ProgramData%\Windows:kernel32.{dll or vbs}
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the following string:
    Cmd /c /rd /s /q C:
  5. If the said string is found, delete the task.

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, locate each task that has the value in the Triggers column:
    • kernel32 = %ProgramData%\Windows:kernel32.{dll or vbs}
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the following string:
    Cmd /c /rd /s /q C:
  5. If the said string is found, delete the task..

Step 6

Search and delete this file

[ 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%\Windows:kernel32.{vbs or dll}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as W2KM_POWMET.CXL. 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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