Analysis by: Jay Garcia
ALIASES:

Trojan-Banker.Win32.Emotet.ennb (Kaspersky); Trojan:Win32/Emotet.ARJ!MTB (Microsft)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

However, as of this writing, the said sites are inaccessible. It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 495,616 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 17 Dec 2019

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:

  • %System%\{random string}{random string}.exe - if run with admin rights
  • %AppDataLocal%\{random string}{random string}\{random string}{random string}.exe - if run without admin rights

(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).)

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\{random string}{random string}
ImagePath = "%System%\{random string}{random string}.exe"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random string}{random string} = %AppDataLocal%\{random string}{random string}\{random string}{random string}.exe

Other System Modifications

This Trojan Spy adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random string}{random string}
DisplayName = "{random string}{random string}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random string}{random string}
Start = "SERVICE_AUTO_START"

Other Details

This Trojan Spy connects to the following possibly malicious URL:

  • http://{BLOCKED}.148.98:8080/kMghVq
  • http://{BLOCKED}.38.252.45:443/25wy2iHgYH
  • http://{BLOCKED}.225.77.21/7hkt6Y2RYb

However, as of this writing, the said sites are inaccessible.

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.564.03
FIRST VSAPI PATTERN DATE: 17 Dec 2019
VSAPI OPR PATTERN File: 15.565.00
VSAPI OPR PATTERN Date: 18 Dec 2019

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.XXPE50FFF033P0005

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\SYSTEM\CurrentControlSet\Services\{random string}{random string}
    • ImagePath = "%System%\{random string}{random string}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{random string}{random string}
    • DisplayName = "{random string}{random string}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\{random string}{random string}
    • Start = "SERVICE_AUTO_START"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random string}{random string} = %AppDataLocal%\{random string}{random string}\{random string}{random string}.exe

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.
  • %System%\{random string}{random string}.exe
  • %AppDataLocal%\{random string}{random string}\{random string}{random string}.exe

Step 7

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