Modified by: Paul Steven Nadera
ALIASES:

Trojan:Win32/Nanocore.BF!MTB (Microsoft); HEUR:Trojan-Dropper.Win32.Generic (Kaspersky)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 1,000,193 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 11 Jun 2020
Payload: Connects to URLs/IPs, Steals information

Arrival Details

This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

This malware arrives via the following means:

Installation

This Backdoor drops the following files:

  • %User Temp%\03836134\awgo.msc
  • %User Temp%\03836134\dbfa.xml
  • %User Temp%\03836134\dwbiukiwwg.bmp
  • %User Temp%\03836134\eeaitaojpi.vog
  • %User Temp%\03836134\emcnlopaex.bmp
  • %User Temp%\03836134\extsxlbjs.xls
  • %User Temp%\03836134\fulpcjqun.pif
  • %User Temp%\03836134\hdpao.log
  • %User Temp%\03836134\iwvudoaq.pdf
  • %User Temp%\03836134\kjnsusd.txt
  • %User Temp%\03836134\kvsqx.vbs
  • %User Temp%\03836134\lujehq.bmp
  • %User Temp%\03836134\mlvxqxapha.msc
  • %User Temp%\03836134\mraln.docx
  • %User Temp%\03836134\nqpxgrjps.ppt
  • %User Temp%\03836134\ohrs.bmp
  • %User Temp%\03836134\ovoa.docx
  • %User Temp%\03836134\qcsx.msc
  • %User Temp%\03836134\rvghvmkrj.msc
  • %User Temp%\03836134\ssaf.ppt
  • %User Temp%\03836134\uantmffea.cpl
  • %User Temp%\03836134\uxgjq.icm
  • %User Temp%\03836134\wmbdfbpme.msc
  • %User Profile%\temp\nqpxgrjps.ppt
  • %User Temp%\RegSvcs.exe
  • %Application Data%\{GUID}\catalog.dat
  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\settings.bin
  • %Application Data%\{GUID}\Logs\{user name}\KB_{Random numbers}.dat
  • %Application Data%\{GUID}\task.dat
  • %Application Data%\{GUID}\storage.dat
  • %Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe -> Admin privilege
  • %Application Data%\{GUID}\{String 1} {String 3}\{String 1}{String 2}.exe -> User privilege

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "%User Temp%\RegSvcs.exe"
  • "schtasks.exe" /create /f /tn "{String 1} {String 3} Task" /xml "%User Temp%\tmp{random characters}.tmp";
  • "schtasks.exe" /create /f /tn "{String 1} {String 3}" /xml "%User Temp%\tmp{random characters}.tmp";
  • "%User Temp%\03836134\fulpcjqun.pif" eeaitaojpi.vog

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

It creates the following folders:

  • %User Profile%\temp
  • %User Temp%\03836134
  • %Program Files%\{String1} {String3}
  • %Application Data%\{GUID}\Logs
  • %Application Data%\{GUID}\Logs\{user name}
  • %Application Data%\{GUID}

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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 adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{GUID}

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{String 1} {String 3} = %Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe -> Admin privilege 32-bit OS

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{String 1} {String 3} = %Application Data%\{GUID}\{String 1} {String 3}\{String 1}{String 2}.exe -> User privilege 32-bit OS

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\
Microsoft\Windows\CurrentVersion\
Run
WindowsUpdate = "0\03836134\fulpcjqun.pif 0\03836134\eeaitaojpi.vog" -> 64-bit OS

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
WindowsUpdate = "0\03836134\fulpcjqun.pif 0\03836134\eeaitaojpi.vog" -> 32-bit OS

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\
Microsoft\Windows\CurrentVersion\
Run
{String 1} {String 3} = %Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe -> Admin privilege 64-bit OS

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\
Microsoft\Windows\CurrentVersion\
Run
{String 1} {String 3} = %Application Data%\{GUID}\{String 1} {String 3}\{String 1}{String 2}.exe -> User privilege 64-bit OS

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Manage its backdoor file:
    • Update itself
    • Restart itself
    • Terminate itself
    • Uninstall itself
    • Restart connection
    • Disconnect
    • Disable/Restore Protection
  • System Control:
    • Restart machine
    • Shutdown machine
    • Lock machine
    • Browse files and folders
    • Task Manager
    • Edit registry
    • Remote console (Command Prompt)
    • Remote execute a file
    • Remote execute a script (Batch, HTML, VBS, Python, Java, PHP)
    • Remote control the machine
    • Remote control mouse
    • Recover browser passwords
    • Log Keystrokes
    • View the screen/webcam
    • Listen to audio/microphone
    • Send Messages / Chat with the malicious user
    • Swap/Unswap mouse buttons
    • Open/Close CD/DVD Tray

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • timnoip.{BLOCKED}s.net:9583
  • {BLOCKED}.{BLOCKED}.225.15:9583

Information Theft

This Backdoor gathers the following data:

  • Computer Name
  • User Name
  • CPU Usage
  • Available and Free Memory
  • Active Window Title
  • Operating System Version
  • System Type (32-bit or 64-bit)
  • Malware Filename
  • Installed Anti-Virus/Anti-Spyware

Other Details

This Backdoor does the following:

  • This backdoor inject the malicious codes to the following processes:
    • %User Temp%\RegSvcs.exe
  • String 1 can be any of the following:
    • dhcp
    • upnp
    • tcp
    • udp
    • saas
    • iss
    • smtp
    • dos
    • dpi
    • pci
    • scsi
    • wan
    • lan
    • nat
    • imap
    • nas
    • ntfs
    • wpa
    • dsl
    • agp
    • arp
    • ddp
    • dns
  • String 2 can be any of the following:
    • ss
    • mon
    • Mgr
    • sv
    • svc
    • host
  • String 3 can be any of the following:
    • Subsystem
    • Monitor
    • Manager
    • Service
    • Host

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

It adds the following scheduled tasks:

  • Task Name: {String 1} {String 3}
  • Action: Start "%User Temp%\RegSvcs.exe" $(Arg0)
  • Task Name: {String 1} {String 3} Task
  • Action: Start "%Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe" $(Arg0)

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000(32-bit), Server 2003(32-bit), XP, Vista(64-bit), 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit) , or C:\Program Files (x86) in Windows XP(64-bit), Vista(64-bit), 7(64-bit), 8(64-bit), 8.1(64-bit), 2008(64-bit), 2012(64-bit) and 10(64-bit).)

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.924.04
FIRST VSAPI PATTERN DATE: 11 Jun 2020
VSAPI OPR PATTERN File: 15.925.00
VSAPI OPR PATTERN Date: 12 Jun 2020

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.XXPE50FSX002

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

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
    • WindowsUpdate = "0\03836134\fulpcjqun.pif 0\03836134\eeaitaojpi.vog"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {String 1} {String 3} = %Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe -> Admin privilege 32-bit OS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {String 1} {String 3} = %Application Data%\{GUID}\{String 1} {String 3}\{String 1}{String 2}.exe -> User privilege 32-bit OS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
    • WindowsUpdate = "0\03836134\fulpcjqun.pif 0\03836134\eeaitaojpi.vog"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
    • {String 1} {String 3} = %Program Files%\{String 1} {String 3}\{String 1}{String 2}.exe -> Admin privilege 64-bit OS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Run
    • {String 1} {String 3} = %Application Data%\{GUID}\{String 1} {String 3}\{String 1}{String 2}.exe -> User privilege 64-bit OS

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.
  • %User Temp%\03836134\awgo.msc
  • %User Temp%\03836134\dbfa.xml
  • %User Temp%\03836134\dwbiukiwwg.bmp
  • %User Temp%\03836134\eeaitaojpi.vog
  • %User Temp%\03836134\emcnlopaex.bmp
  • %User Temp%\03836134\extsxlbjs.xls
  • %User Temp%\03836134\fulpcjqun.pif
  • %User Temp%\03836134\hdpao.log
  • %User Temp%\03836134\iwvudoaq.pdf
  • %User Temp%\03836134\kjnsusd.txt
  • %User Temp%\03836134\kvsqx.vbs
  • %User Temp%\03836134\lujehq.bmp
  • %User Temp%\03836134\mlvxqxapha.msc
  • %User Temp%\03836134\mraln.docx
  • %User Temp%\03836134\nqpxgrjps.ppt
  • %User Temp%\03836134\ohrs.bmp
  • %User Temp%\03836134\ovoa.docx
  • %User Temp%\03836134\qcsx.msc
  • %User Temp%\03836134\rvghvmkrj.msc
  • %User Temp%\03836134\ssaf.ppt
  • %User Temp%\03836134\uantmffea.cpl
  • %User Temp%\03836134\uxgjq.icm
  • %User Temp%\03836134\wmbdfbpme.msc
  • %User Profile%\temp\nqpxgrjps.ppt
  • %User Temp%\RegSvcs.exe
  • %Program Files%\{String1} {String3}\{String1}{String2}.exe <- Admin Privilege
  • %Application Data%\{GUID}\{String1} {String3}\{String1}{String2}.exe <- User Privilege
  • %Application Data%\{GUID}\catalog.dat
  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\settings.bin
  • %Application Data%\{GUID}\Logs\{user name}\KB_{Random numbers}.dat
  • %Application Data%\{GUID}\task.dat
  • %Application Data%\{GUID}\storage.dat

Step 7

Search and delete these folders

[ 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%\{GUID}
  • %Application Data%\{GUID}\Logs
  • %Application Data%\{GUID}\Logs\{user name}
  • %Application Data%\{GUID}\{String1} {String3}
  • %User Profile%\temp
  • %User Temp%\03836134

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.NANOCORE.TIAOODHN. 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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