Analysis by: John Rey Canon

ALIASES:

Trojan:Win32/TrickBot.CD!MTB (Microsoft); Trojan.Win32.Trickbot (Ikarus); Win32/TrickBot.CX (ESET-NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan Spy 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: 417,792 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 20 Dec 2019

Arrival Details

This Trojan Spy 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 Spy adds the following folders:

  • %Application Data%\taskhealth

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It drops the following files:

  • %System%\Tasks\Task Health Application

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It drops the following copies of itself into the affected system:

  • %Application Data%\taskhealth\{Malware Filename}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Trojan Spy adds the following registry keys:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
Sketch

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
Sketch\Recent File List

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications\
Sketch\Settings

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\DefaultIcon

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\open

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\open\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\print

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\print\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\printto

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\printto\
command

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.skh

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.skh\ShellNew

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document
{Default} = Sketch Document

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\DefaultIcon
{Default} = {Malware Filename}.exe,1

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\open\
command
{Default} = {Malware Filename}.exe "%1"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\print\
command
{Default} = {Malware Filename}.exe /p "%1"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Sketch.Document\shell\printto\
command
{Default} = {Malware Filename}.exe /pt "%1" "%2" "%3" "%4"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.skh
{Default} = Sketch.Document

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.skh\ShellNew
NullFile = ""

Other Details

This Trojan Spy does the following:

  • It adds the following scheduled tasks:
    • Task Name: Task Health Application
    • Trigger: At system startup; repeat every 00:12:00 for a duration of 412.10:30:00
    • Action: %Application Data%\taskhealth\{Malware Filename}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.576.06
FIRST VSAPI PATTERN DATE: 23 Dec 2019
VSAPI OPR PATTERN File: 15.577.00
VSAPI OPR PATTERN Date: 24 Dec 2019

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

Identify and terminate files detected as TrojanSpy.Win32.TRICKBOT.TIGOCFF

[ 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

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Task Name: Task Health Application
  • Task to be run: %Application Data%\taskhealth\{Malware Filename}.exe

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 Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, 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 Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 5

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\Classes\Sketch.Document
    • {Default} = Sketch Document
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\DefaultIcon
    • {Default} = {Malware Filename}.exe,1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\open\command
    • {Default} = {Malware Filename}.exe "%1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\print\command
    • {Default} = {Malware Filename}.exe /p "%1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\printto\command
    • {Default} = {Malware Filename}.exe /pt "%1" "%2" "%3" "%4"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.skh
    • {Default} = Sketch.Document
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.skh\ShellNew
    • NullFile = ""

Step 6

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\Software
    • Local AppWizard-Generated Applications = ""
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
    • Sketch = ""
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
    • Sketch\Recent File List = ""
  • In HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications
    • Sketch\Settings = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • Sketch.Document = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document
    • DefaultIcon = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document
    • shell = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell
    • open = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\open
    • command = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell
    • print = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\print
    • command = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell
    • printto = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Sketch.Document\shell\printto
    • command = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
    • .skh = ""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.skh
    • ShellNew = ""

Step 7

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.  
  • %System%\Tasks\Task Health Application
  • %Application Data%\taskhealth\{Malware Filename}.exe

Step 8

Search and delete this folder

[ 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.
  • %Application Data%\taskhealth

Step 9

Scan your computer with your Trend Micro product to delete files detected as TrojanSpy.Win32.TRICKBOT.TIGOCFF. 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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