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TrojanSpy.Win32.EMOTET.THCBFAI

March 27, 2019
 Analysis by: Earle Maui Earnshaw
 ALIASES:

Trojan:Win32/Fuerboos.C!cl (Microsoft); Win32.Outbreak (Ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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.

It connects to certain websites to send and receive information. It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

248,072 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Mar 2019

Payload:

Connects to URLs/IPs, Steals information

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 drops the following copies of itself into the affected system and executes them:

  • %System%\{string1}{string2}.exe - if run with admin privileges
  • %AppDataLocal%\{string1}{string2}\{string1}{string2}.exe if run without admin privileges
    {string1} and {string2} are randomly chosen from the following strings:
    • adam
    • admin
    • alaska
    • avatar
    • avg
    • based
    • cbs
    • culture
    • daf
    • dasmrc
    • define
    • detect
    • dev
    • diag
    • eap
    • earcon
    • enroll
    • form
    • gen
    • guids
    • idl
    • indexer
    • iprop
    • iss
    • jersey
    • lime
    • mapi
    • mdmmcd
    • menus
    • meta
    • mfidl
    • mini
    • mouse
    • neutral
    • not
    • panes
    • pnp
    • polic
    • radar
    • repl
    • resw
    • right
    • ripple
    • sat
    • serv
    • shader
    • single
    • slide
    • source
    • started
    • subs
    • svcs
    • thunk
    • tmpl
    • tuip
    • turned
    • uuidgen
    • vsc
    • wab
    • wcs
    • wfp
    • wgx
    • without
    • wordpad
    • zip

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It adds the following processes:

  • {Malware File Path}\{Malware File Name}.exe --{8 Random Characters}
  • "%AppDataLocal%\{string1}{string2}\{string1}{string2].exe" = if run without admin privileges
  • "%AppDataLocal%\{string1}{string2}\{string1}{string2].exe" --{8 Random Characters} = if run without admin privileges
  • "%System%\{string1}{string2].exe" = if run with admin privileges
  • "%System%\{string1}{string2].exe" --{8 Random Characters} = if run with admin privileges

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

  • %AppDataLocal%\{string1}{string2} - If run without admin privileges

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

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

  • Global\I{Volume Serial Number}
  • Global\M{Volume Serial Number}

Autostart Technique

This Trojan Spy registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
Type = 16

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
ErrorControl = 0

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
ImagePath = %System%\{string1}{string2}.exe

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
DisplayName = {string1}{string2}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
ObjectName = LocalSystem

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{string1}{string2} = %AppDataLocal%\{string1}{string2}\{string1]{string2}.exe

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}

Information Theft

This Trojan Spy gathers the following data:

  • Computer Name
  • System Locale
  • OS Version
  • Running Processes

Other Details

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

  • {BLOCKED}.{BLOCKED}.129.88/{string/s}
  • {BLOCKED}.{BLOCKED}.61.94/{string/s}
  • {BLOCKED}.{BLOCKED}.182.236:7080/{string/s}
  • {BLOCKED}.{BLOCKED}.145.96:8090/{string/s}
  • {BLOCKED}.{BLOCKED}.152.129:8443/{string/s}
  • {BLOCKED}.{BLOCKED}.144.197:7080/{string/s}
  • {BLOCKED}.{BLOCKED}.193.173/{string/s}
    Strings are randomly chosen from the following:
    • acquire
    • add
    • arizona
    • attrib
    • badge
    • balloon
    • ban
    • between
    • bml
    • cab
    • child
    • chunk
    • codec
    • cone
    • cookies
    • dev
    • dma
    • enable
    • enabled
    • entries
    • forced
    • free
    • glitch
    • guids
    • health
    • iab
    • ices
    • img
    • iplk
    • jit
    • json
    • loadan
    • merge
    • mult
    • nsip
    • odbc
    • pdf
    • pnp
    • prep
    • prov
    • psec
    • publish
    • raster
    • report
    • results
    • ringin
    • rtm
    • schema
    • scripts
    • sess
    • site
    • splash
    • srvc
    • stubs
    • sym
    • symbols
    • taskbar
    • teapot
    • tlb
    • tpt
    • usbccid
    • vermont
    • walkl
    • window
    • xian

It does the following:

  • It accepts the following arguments to perform its routine:
    • {Malware File Path}\{Malware File Name}.exe --{8 Random Characters} = Used for dropping the copy to %System% or %AppDataLocal%
    • %System%\{string1}{string2}.exe --{8 Random Characters} = When run as admin needed arguments to perform its routine
    • %AppDataLocal%\{string1}{string2}\{string1}{string2}.exe --{8 Random Characters} = When not run as admin needed arguments to perform its routine
  • It will create a startup service if it has admin privileges, otherwise it will only create an autorun entry in the registry.

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.896.05

FIRST VSAPI PATTERN DATE:

26 Mar 2019

VSAPI OPR PATTERN File:

14.897.00

VSAPI OPR PATTERN Date:

27 Mar 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

Restart in Safe Mode

[ Learn More ]

Step 4

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.

 
  • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\devslide

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • devslide = "C:\Users\{BLOCKED}er_732\AppData\Local\devslide\devslide.exe"

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TrojanSpy.Win32.EMOTET.THCBFAI. 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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