Analysis by: Francis Xavier Antazo
ALIASES:

Trojan:Win32/Emotet.G (Microsoft), Win32/Emotet.AD (ESET-NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email, Downloaded from the Internet

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size: 205,851 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 May 2015
Payload: Connects to URLs/IPs, Downloads files

Arrival Details

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

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %AppDataLocal%\{random characters}.exe

(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.)

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

  • _{explorer.exe process id hexadecimal}{short random characters}

It injects threads into the following normal process(es):

  • explorer.exe

Autostart Technique

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

HKCU\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters} = %AppDataLocal%\{random characters}.exe

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.{random characters}\E

HKEY_CLASSES_ROOT\.{random characters}\Q

HKEY_CLASSES_ROOT\.{random characters}\W

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.233.226:8080
  • http://{BLOCKED}.{BLOCKED}.252.88:8080
  • http://{BLOCKOED}.{BLOCKED}.171.85:8080
  • http://{BLOCKED}.{BLOCKED}.2.168:8080
  • {BLOCKED}aautodiagnostic.com/modules/mod_aratipas/ex_mss3.exe

NOTES:

The downloaded files are dropped in %User Temp% folder.

The downloaded files are detected as variants of TROJ_ROWLIM.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.664.04
FIRST VSAPI PATTERN DATE: 12 May 2015
VSAPI OPR PATTERN File: 11.665.00
VSAPI OPR PATTERN Date: 13 May 2015

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

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • {random characters} = “%Application Data%\{random characters}.exe”

Step 4

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. DATA_GENERIC
  • In the Look In drop-down list, select My Computer then press Enter.
  • Once located, select the file then press SHIFT+DELETE to delete it.
    *Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).

    • • For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

    1. Open a Windows Explorer window.
      • For Windows Vista, 7, and Server 2008 users, click Start>Computer.
      • For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
    2. In the Search Computer/This PC input box, type:
      DATA_GENERIC
    3. Once located, select the file then press SHIFT+DELETE to delete it.
      *Note: Read the following Microsoft page if these steps do not work on Windows 7.

    Step 5

    The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

     
    • In HKEY_CLASSES_ROOT\.{random characters}
      • E
    • In HKEY_CLASSES_ROOT\.{random characters}
      • Q
    • In HKEY_CLASSES_ROOT\.{random characters}
      • W

    Step 6

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

    Step 7

    Remove malware/grayware files dropped/downloaded by TSPY_EMOTET.XXRJ. (Note: Please skip this step if the threats listed below have already been removed.)


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