Analysis by: Anthony Joe Melgarejo
ALIASES:

TrojanDownloader:Win32/Banload.BFQ (Microsoft), Win32/TrojanDownloader.Banload.XBU (ESET-NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 209,920 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 05 Aug 2016
Payload: Downloads files

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.

Download Routine

This Trojan accesses websites to download the following files:

  • http://{BLOCKED}k.de/cro/chsh.zlib

It saves the files it downloads using the following names:

  • %AppDataLocal%\{14 alpha-numeric characters}\fieldbus.zlib

(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.)

As of this writing, the said sites are inaccessible.

NOTES:

The downloaded file %AppDataLocal%\{14 alpha-numeric characters}\fieldbus.zlib is an archive that may contain the following files:

  • fonrtsdls.exe
  • merupakan.exe
  • wuwebv.dll

It then extracts the said files in the same directory.

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.848.05
FIRST VSAPI PATTERN DATE: 20 Oct 2016
VSAPI OPR PATTERN File: 12.849.00
VSAPI OPR PATTERN Date: 21 Oct 2016

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 folder

[ 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%\{14 alpha-numeric characters}

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_BANLOAD.YWNRM. 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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