Analysis by: Francis Xavier Antazo

ALIASES:

Win32/Emotet.AG (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: Downloaded from the Internet

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be downloaded from remote sites by other malware.

  TECHNICAL DETAILS

File Size: 205,851 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 13 May 2015
Payload: Connects to URLs/IPs, Downloads files, Sends messages

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It may be downloaded from remote site(s) by the following malware:

  • TROJ_EMOTET variants

Installation

This Trojan drops the following files:

  • %User Temp%\mailsend{random characters}

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

  • {BLOCKED}.{BLOCKED}.160.145/{random characters 1}/{random characters}
  • {BLOCKED}.{BLOCKED}.209.149:8080/{random characters 1}/{random characters}
  • {BLOCKED}.{BLOCKED}.214.106:443/{random characters 1}/{random characters}

It saves the files it downloads using the following names:

  • %User Temp%\{random filename}.tmp - {spam pdf or html file}

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

NOTES:

This Trojan can send spam email that contain .PDF files, which contain a link that leads to the download of a .ZIP file. The .ZIP file contains a malware belonging to TROJ_EMOTET.

It can also send spam email that contain a malicious link. The link leads to the download of a .ZIP file. The .ZIP file contains a malware belonging to TROJ_EMOTET.

The languages it uses are German and Polish.

It downloads its list of Simple Mail Transfer Protocol (SMTP) servers and the credentials to use from its C&C server.

  SOLUTION

Minimum Scan Engine: 9.750
FIRST VSAPI PATTERN FILE: 11.666.05
FIRST VSAPI PATTERN DATE: 13 May 2015
VSAPI OPR PATTERN File: 11.667.00
VSAPI OPR PATTERN Date: 14 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

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.  
  • %User Temp%\mailsend{random characters}
  • %User Temp%\{random filename}.tmp

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_ROWLIM.A. 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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