Analysis by: Joselyn Canuela

 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 as an attachment to email messages spammed by other malware/grayware or malicious users. It 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 the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system. As of this writing, the said sites are inaccessible.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 86,016 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Aug 2017
Payload: Downloads files

Arrival Details

This Trojan Spy arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It 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 and executes the following files:

  • %AppDataLocal%\Microsoft\Windows\{string 1}{string 2}.exe - drops the file here if it has no admin privileges, also detected as TSPY_EMOTET.AUSJKV
  • %System%\{string 1}{string 2}.exe - drops the file here if it has admin privileges, also detected as TSPY_EMOTET.AUSJKV

    where {string 1} and {string 2} is a combination of any of the following strings:
    • agent
    • app
    • audio
    • bio
    • bits
    • cache
    • card
    • cart
    • cert
    • com
    • crypt
    • dcom
    • defrag
    • device
    • dhcp
    • dns
    • event
    • evt
    • flt
    • gdi
    • group
    • help
    • home
    • host
    • info
    • iso
    • launch
    • log
    • logon
    • lookup
    • man
    • math
    • mgmt
    • msi
    • ncb
    • net
    • nv
    • nvidia
    • proc
    • prop
    • prov
    • provider
    • reg
    • rpc
    • screen
    • search
    • sec
    • server
    • service
    • shed
    • shedule
    • spec
    • srv
    • storage
    • svc
    • sys
    • system
    • task
    • time
    • video
    • view
    • win
    • window
    • wlan
    • wmi

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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

  • M{hash of full file path}
  • 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\CurrentControlSet\
services\{string 1}{string 2}
ImagePath = %System%\{string 1}{string 2}.exe
where {string 1} and {string 2} is the same name as the drop file

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{string 1}{string 2} = "%AppDataLocal%\Microsoft\Windows\{string 1}{string 2}.exe

Download Routine

This Trojan Spy connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}.{BLOCKED}.159.58:443/
  • http://{BLOCKED}.{BLOCKED}.252.178:8080/
  • http://{BLOCKED}.{BLOCKED}.245.37:7080
  • http://{BLOCKED}.{BLOCKED}.1.167:8080
  • http://{BLOCKED}.{BLOCKED}.212.79:443
  • http://{BLOCKED}.{BLOCKED}.192.45:8080
  • http://{BLOCKED}.{BLOCKED}.131.20:8080
  • http://{BLOCKED}.{BLOCKED}.33.200:8080

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

As of this writing, the said sites are inaccessible.

Other Details

This Trojan Spy does the following:

  • It will create a startup service if it has admin privileges, otherwise it will only create an autorun entry in the registry.

It deletes the initially executed copy of itself

NOTES:
Information Theft

This Trojan Spy gathers the following data:

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

  •   SOLUTION

    Minimum Scan Engine: 9.850
    FIRST VSAPI PATTERN FILE: 13.598.02
    FIRST VSAPI PATTERN DATE: 16 Aug 2017
    VSAPI OPR PATTERN File: 13.599.00
    VSAPI OPR PATTERN Date: 17 Aug 2017

    Step 1

    Before doing any scans, Windows XP, Windows Vista, and Windows 7 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, and then 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\CurrentControlSet\services
      • {string 1}{string 2}

    Step 4

    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.

     
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {string 1}{string 2} = "%AppDataLocal%\Microsoft\Windows\{string 1}{string 2}.exe

    Step 5

    Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_EMOTET.AUSJKV. 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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