TrojanSpy.Win32.EMOTET.THDBEAI

July 31, 2019
 Analysis by: Wilbert Luy
 ALIASES:

Trojan:Win32/Emotet.PC!MTB (Microsoft), Trojan-Banker.Win32.Emotet.dbcv (Kaspersky)

 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:

Downloaded from the Internet, Dropped by other malware

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 itself after execution.

  TECHNICAL DETAILS

File Size:

79,872 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Sep 2018

Payload:

Connects to URLs/IPs, Modifies system registry, Steals information, Deletes self after execution

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:
    • rel
    • tables
    • glue
    • impl
    • texture
    • related
    • key
    • nis
    • langs
    • iprop
    • exec
    • wrap
    • matrix
    • dump
    • phoenix
    • ribbon
    • sorting
    • pinned
    • lics
    • bit
    • unpack
    • adt
    • rep
    • jobs
    • acl
    • title
    • sound
    • events
    • targets
    • scrn
    • mheg
    • lines
    • prompt
    • adjust
    • xian
    • ser
    • cycle
    • redist
    • its
    • boxes
    • dma
    • small
    • cloud
    • flow
    • guiddef
    • whole
    • parent
    • bears
    • random
    • bulk
    • idebug
    • viewer
    • starta
    • comment
    • sel
    • source
    • hotspot
    • pnf
    • portal
    • sitka
    • iell
    • slide
    • typ
    • sonic

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local 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\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%\{string 1}{string 2}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\{string1}{string2}
DisplayName = "{string 1}{string 2}"

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}

Other System Modifications

This Trojan Spy modifies the following registry entries:

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings
ProxyEnable = "0"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\Connections
DefaultConnectionSettings = "{Hex Data}"

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings\Connections
SavedLegacySettings = "{Hex Data}"

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}.130.39/{string/s}
  • {BLOCKED}.{BLOCKED}.68.186/{string/s}
  • {BLOCKED}.{BLOCKED}.228.47/{string/s}
  • {BLOCKED}.{BLOCKED}.9.18/{string/s}
  • {BLOCKED}.{BLOCKED}.156.30/{string/s}
    Strings are randomly chosen from the following:
    • Teapot
    • pnp
    • tpt
    • splash
    • site
    • codec
    • health
    • balloon
    • cab
    • odbc
    • badge
    • dma
    • psec
    • cookies
    • iplk
    • devices
    • enable
    • mult
    • prov
    • vermont
    • attrib
    • schema
    • iab
    • chunk
    • publish
    • prep
    • srvc
    • sess
    • ringin
    • nsip
    • stubs
    • img
    • add
    • xian
    • jit
    • free
    • pdf
    • loadan
    • arizona
    • tlb
    • forced
    • results
    • symbols
    • report
    • guids
    • taskbar
    • child
    • cone
    • glitch
    • entries
    • between
    • bml
    • usbccid
    • sym
    • enabled
    • merge
    • window
    • scripts
    • raster
    • acquire
    • json
    • rtm
    • walk
    • bang

It does the following:

  • It deletes the previous version of EMOTET in the system.
    %AppDataLocal%\{string1}{string2}
    %System%\{string1}{string2].exe
    Based on the following strings:
    • not
    • ripple
    • svcs
    • serv
    • wab
    • shader
    • single
    • without
    • wcs
    • define
    • eap
    • culture
    • slide
    • zip
    • tmpl
    • mini
    • polic
    • panes
    • earcon
    • menus
    • detect
    • form
    • uuidgen
    • pnp
    • admin
    • tuip
    • avatar
    • started
    • dasmrc
    • alaska
    • guids
    • wfp
    • adam
    • wgx
    • lime
    • indexer
    • repl
    • dev
    • mapi
    • resw
    • daf
    • diag
    • iss
    • vsc
    • turned
    • neutral
    • sat
    • source
    • enroll
    • mfidl
    • idl
    • based
    • right
    • cbs
    • radar
    • avg
    • wordpad
    • metagen
    • mouse
    • iprop
    • mdmmcd
    • jersey
    • thunk
    • subs
  • It will create a startup service if it has admin privileges, otherwise it will only create an autorun entry in the registry.

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

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.962.03

FIRST VSAPI PATTERN DATE:

26 Apr 2019

VSAPI OPR PATTERN File:

14.963.00

VSAPI OPR PATTERN Date:

27 Apr 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.

 
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services
    • {string 1}{string 2}

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
    • {string 1}{string 2} = "%AppDataLocal%\{string 1}{string 2}\{string 1}{string 2}.exe"

Step 6

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_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyEnable = "0"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyEnable = "{Default Value}"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • SavedLegacySettings = "{Hex Data}"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • SavedLegacySettings = "{Default Value}"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • DefaultConnectionSettings = "{Hex Data}"
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
    • DefaultConnectionSettings = "{Default Value}"

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.
  • %AppDataLocal%\{string1}{string2}

Step 8

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