Analysis by: Anthony Joe Melgarejo
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 387,584 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 17 Dec 2015

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 copies of itself into the affected system:

  • %User Temp%\{8 random numbers}

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on 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 Trojan drops the following files:

  • %Windows%\Tasks\{random GUID 1}.job - for Windows XP and prior

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

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Console\%SystemRoot%_System32_WindowsPowerShell_v1.0_powershell.exe

HKEY_CURRENT_USER\Console\%SystemRoot%_System32_svchost.exe

HKEY_CURRENT_USER\Console\taskeng.exe

It adds the following registry entries:

HKEY_CURRENT_USER\Console\%SystemRoot%_System32_WindowsPowerShell_v1.0_powershell.exe
WindowPosition = "201329664"

HKEY_CURRENT_USER\Console\%SystemRoot%_System32_svchost.exe
WindowPosition = "201329664"

HKEY_CURRENT_USER\Console\taskeng.exe
WindowPosition = "201329664"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
NameServer = "82.163.142.3 95.211.158.130"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
DHCPNameServer = "82.163.142.3"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{random GUID 2}
DHCPNameServer = "82.163.142.3"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{random GUID 2}
NameServer = "82.163.142.3 95.211.158.130"

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.184.10
  • http://{BLOCKED}s.net
  • http://{BLOCKED}u.org/u/
  • http://{BLOCKED}fun.info/u/
  • http://{BLOCKED}s.info/u/
  • http://{BLOCKED}lmy.info/u/
  • http://{BLOCKED}o.info/u/
  • http://{BLOCKED}o.info/u/
  • http://{BLOCKED}a.info
  • http://{BLOCKED}rut.info/u/
  • http://{BLOCKED}cool.info/u/
  • http://{BLOCKED}cool.net/u/
  • http://{BLOCKED}set.info/u
  • http://{BLOCKED}as.info/u/
  • http://{BLOCKED}.info/u/
  • http://{BLOCKED}ljob.info/u/
  • http://{BLOCKED}h.info
  • http://{BLOCKED}h.net
  • http://{BLOCKED}suns.info/u/
  • http://{BLOCKED}tnew.net/u/
  • http://{BLOCKED}et.biz/u/
  • http://{BLOCKED}bmy.com/u/
  • http://{BLOCKED}un.info/u/
  • http://{BLOCKED}s.net/u/
  • http://{BLOCKED}i.info

NOTES:

It uses the Windows Task Scheduler to add a scheduled task that executes a powershell script. The scheduled task executes the script every day (at a random hour per machine).

The scheduled task has the following command line to execute the powershell script:

%System%\WindowsPowershell\v1.0\powershell.exe -windowstyle hidden -noninteractive -ExecutionPolicy bypass -EncodedCommand {Base64-encoded script}

  SOLUTION

Minimum Scan Engine: 9.800

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 the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

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

  1. Open the Windows Scheduled Tasks. To do this, click Start>Programs>Accessories>System Tools>Scheduled Tasks.
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the .JOB file. To do this, check the value in the Run field.
  4. If found, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

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 of the Task Scheduler Window, click Task Scheduler Library.
  3. In the upper-middle panel, click a Task.
  4. In the lower middle panel, click the Actions tab
  5. Check if the malware path and file name exists in the task. To do this, check the value in the Details column under the Actions tab.
  6. If found, select the task and press DELETE and click Yes to delete the task.
  7. Repeat the steps above for the remaining tasks.

Step 4

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\Tcpip\Parameters
    • From: NameServer = "82.163.142.3 95.211.158.130"
      To: NameServer = {user-defined}
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • From: DHCPNameServer = "82.163.142.3"
      To: DHCPNameServer = {user-defined}
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{random GUID 2}
    • From: NameServer = "82.163.142.3 95.211.158.130"
      To: NameServer = {user-defined}
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{random GUID 2}
    • From: DHCPNameServer = "82.163.142.3"
      To: DHCPNameServer = {user-defined}

Step 5

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.

 
  • In HKEY_CURRENT_USER\Console
    • %SystemRoot%_System32_WindowsPowerShell_v1.0_powershell.exe
  • In HKEY_CURRENT_USER\Console
    • %SystemRoot%_System32_svchost.exe
  • In HKEY_CURRENT_USER\Console
    • taskeng.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DNSCHANGER.JJ. 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.

NOTES:

Look for the command line for executing the powershell script to delete the scheduled task created by this malware.


Did this description help? Tell us how we did.