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Trojan.Win32.SMOKELOADER.C

March 13, 2024
 Analysis by: John Rainier Navato
 ALIASES:

TrojanDownloader:Win32/Dofoil.AS (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Propagates via network shares


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.

As of this writing, the said sites are inaccessible.

It terminates itself if it detects it is being run in a virtual environment.

  TECHNICAL DETAILS

File Size:

336,896 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Jul 2019

Payload:

Connects to URLs/IPs, Drops 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 drops the following copies of itself into the affected system:

  • %AppData%\{File Name Generated From a Portion of its Mutex}

It drops the following files:

  • %User Temp%\4DD3.tmp → copy of %System%\ntdll.dll
  • %AppData%\{File Name Generated From a Portion of its Mutex} → XML file used to run the dropped copy

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

It adds the following processes:

  • {Malware File Path}\{Malware File Name}.{Malware File Extension}

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {MD5 hash of {ComputerName}D781F33C{Volume Serial Number}}{Volume Serial Number}FF

It injects codes into the following process(es):

  • explorer.exe

Other System Modifications

This Trojan deletes the following files:

  • %Application Data%\{Dropped Copy}:Zone.Identifier

(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).)

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • Autoruns.exe
  • idaq.exe
  • idaq64.exe
  • idaw.exe
  • idaw64.exe
  • ollydbg.exe
  • ProcessHacker.exe
  • procexp.exe
  • procexp64.exe
  • procmon.exe
  • procmon64.exe
  • Tcpview.exe
  • Wireshark.exe
  • x32dbg.exe
  • x64dbg.exe

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}service01242505.ru/
  • http://{BLOCKED}service012505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}-01242505.tk/
  • http://{BLOCKED}-01252505.ml/
  • http://{BLOCKED}-01262505.ga/
  • http://{BLOCKED}-01272505.cf/
  • http://{BLOCKED}-01282505.gq/
  • http://{BLOCKED}-01292505.com/
  • http://{BLOCKED}-01302505.net/
  • http://{BLOCKED}-01312505.org/
  • http://{BLOCKED}-01322505.biz/
  • http://{BLOCKED}t-01332505.info/
  • http://{BLOCKED}t-01342505.eu/
  • http://{BLOCKED}t-01352505.nl/
  • http://{BLOCKED}t-01362505.mobi/
  • http://{BLOCKED}t-01372505.name/
  • http://{BLOCKED}t-01382505.me/
  • http://{BLOCKED}t-01392505.garden/
  • http://{BLOCKED}t-01402505.art/
  • http://{BLOCKED}t-01412505.band/
  • http://{BLOCKED}t-01422505.bargains/
  • http://{BLOCKED}t-01432505.bet/
  • http://{BLOCKED}t-01442505.blue/
  • http://{BLOCKED}t-01452505.business/
  • http://{BLOCKED}t-01462505.casa/
  • http://{BLOCKED}t-01472505.city/
  • http://{BLOCKED}t-01482505.click/
  • http://{BLOCKED}t-01492505.company/
  • http://{BLOCKED}t-01502505.futbol/
  • http://{BLOCKED}t-01512505.gallery/
  • http://{BLOCKED}t-01522505.game/
  • http://{BLOCKED}t-01532505.games/
  • http://{BLOCKED}t-01542505.graphics/
  • http://{BLOCKED}t-01552505.group/
  • http://{BLOCKED}t-02252505.ml/
  • http://{BLOCKED}t-02262505.ga/
  • http://{BLOCKED}t-02272505.cf/
  • http://{BLOCKED}t-02282505.gq/
  • http://{BLOCKED}t-03252505.ml/
  • http://{BLOCKED}t-03262505.ga/
  • http://{BLOCKED}t-03272505.cf/
  • http://{BLOCKED}t-03282505.gq/
  • http://{BLOCKED}t-05242505.tk/
  • http://{BLOCKED}t-06242505.tk/
  • http://{BLOCKED}t-service01242505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}-service01242505.ru/
  • http://{BLOCKED}-service012505.ru/
  • http://{BLOCKED}st-service012505.ru/
  • http://{BLOCKED}est-service012505.ru/
  • http://{BLOCKED}ervice01242505.ru/
  • http://{BLOCKED}ervice012505.com/
  • http://{BLOCKED}ervice012505.eu/
  • http://{BLOCKED}ervice012505.fun/
  • http://{BLOCKED}ervice012505.host/
  • http://{BLOCKED}ervice012505.info/
  • http://{BLOCKED}ervice012505.net/
  • http://{BLOCKED}rvice012505.net2505.ru/
  • http://{BLOCKED}rvice012505.online/
  • http://{BLOCKED}rvice012505.org2505.ru/
  • http://{BLOCKED}rvice012505.pp2505.ru/
  • http://{BLOCKED}rvice012505.press/
  • http://{BLOCKED}rvice012505.pro/
  • http://{BLOCKED}rvice012505.pw/
  • http://{BLOCKED}rvice012505.ru.com/
  • http://{BLOCKED}rvice012505.site/
  • http://{BLOCKED}rvice012505.space/
  • http://{BLOCKED}rvice012505.store/
  • http://{BLOCKED}rvice012505.su/
  • http://{BLOCKED}rvice012505.tech/
  • http://{BLOCKED}rvice012505.website/
  • http://{BLOCKED}rvice012505.xyz/
  • http://{BLOCKED}rvice01blog2505.ru/
  • http://{BLOCKED}rvice01club2505.ru/
  • http://{BLOCKED}rvice01dom2505.ru/
  • http://{BLOCKED}rvice01forum2505.ru/
  • http://{BLOCKED}rvice01info2505.ru/
  • http://{BLOCKED}rvice01land2505.ru/
  • http://{BLOCKED}rvice01life2505.ru/
  • http://{BLOCKED}rvice01plus2505.ru/
  • http://{BLOCKED}rvice01pro2505.ru/
  • http://{BLOCKED}rvice01rus2505.ru/
  • http://{BLOCKED}rvice01shop2505.ru/
  • http://{BLOCKED}rvice01stroy2505.ru/
  • http://{BLOCKED}rvice01torg2505.ru/
  • http://{BLOCKED}t-service012505.ru/
  • http://{BLOCKED}t-service012505.ru/

As of this writing, the said sites are inaccessible.

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • http://www.{BLOCKED}si.com/ncsi.txt

It sets the attributes of the following file(s) to Hidden and System:

  • %AppData%\{File Name Generated From a Portion of its Mutex} → dropped copy
  • %AppData%\{File Name Generated From a Portion of its Mutex} → XML file used to run the dropped copy

It terminates itself if it detects it is being run in a virtual environment.

It does the following:

  • It terminates itself if the system keyboard language is one of the following:
    • Russian
    • Ukrainian
  • It terminates processes with the following window class names:
    • Autoruns
    • PROCEXPL
    • PROCMON_WINDOW_CLASS
    • ProcessHacker
    • OllyDBG
    • TcpViewClass
  • It must be executed on machines using the following Windows version:
    • Vista or newer
  • It deletes itself if it detects that it is not running as %AppData%\{File Name Generated From a Portion of its Mutex}

It checks if the following virtual machine or sandbox related module(s) is loaded in the affected system:

  • sbiedll

It checks if the following virtual machine- or sandbox-related registry keys are present in the affected system:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControLSet\
Enum\SCSI\{VM String}
where VM String = qemu; virtio; vmware; vbox; xen =

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControLSet\
Enum\IDE\{VM String}
where VM String = qemu; virtio; vmware; vbox; xen =

It does not proceed to its malicious routine if it detects that it is being debugged.

It adds the following scheduled tasks:

  • Task Name: NvNgxUpdateCheckDaily_{78821544-1544-1544-1544-788215441544}
    Task Action: regsvr32 /s /n /u /i:"%Application Data%\{XML File}" scrobj

(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:

9.800

FIRST VSAPI PATTERN FILE:

19.204.05

FIRST VSAPI PATTERN DATE:

08 Mar 2024

VSAPI OPR PATTERN File:

19.205.00

VSAPI OPR PATTERN Date:

09 Mar 2024

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

    • TROJ.Win32.TRX.XXPE50FFF078

Step 2

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 3

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 4

Restart in Safe Mode

[ Learn More ]

Step 5

Deleting Scheduled Tasks while in Safe Mode

  1. Still in safe mode, the following {Task Name}-{Task to be run} listed should be used in the steps identified below:
    • Task Name: NvNgxUpdateCheckDaily_{78821544-1544-1544-1544-788215441544}
    • Task to be run: regsvr32 /s /n /u /i:"%Application Data%\{XML File}" scrobj
  2. For Windows 7 and Server 2008 (R2) users, click Start>Computer.
    • For Windows 8, 8.1, 10, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
  3. In the Search Computer/This PC input box, type:
    • %System%\Tasks\{Task Name}
  4. Once located, select the file then press SHIFT+DELETE to delete it.
  5. Open Registry Editor. To do this:
    • For Windows 7 and Server 2008 (R2) users, click the Start button, type regedit in the Search input field, and press Enter.
    • For Windows 8, 8.1, 10, and Server 2012 (R2) users, right-click on the lower left corner of the screen, click Run, type regedit in the text box
  6. In the left panel of the Registry Editor window, double-click the following:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
  7. Locate the created entry and take note of the registry value's data:
    • ID={Task Data}
  8. After taking note of the data, delete the registry key:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tree>{Task Name}
  9. In the left panel of the Registry Editor window, double-click the following:
    • HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Schedule>TaskCache>Tasks
  10. Still in the left panel, locate and delete the registry key with the same name as the located Task Data in step #6:
    • ={Task Data}
  11. Close Registry Editor.

Step 6

Search and delete these files

[ 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.
  • %User Temp%\4DD3.tmp
  • %AppData%\{File Name Generated from a Portion of its Mutex}
  • %AppData%\{File Name Generated from a Portion of its Mutex}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.SMOKELOADER.C. 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.

Step 8

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.SMOKELOADER.C. 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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