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BKDR_ZXSHELL.WNZ

August 16, 2018
 Analysis by: Maureen Reyes
 ALIASES:

Trojan:Win32/Occamy.C (Microsoft), Trojan-Dropper.Win32.Agent (ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size:

3,463,584 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

07 Aug 2018

Arrival Details

This Backdoor 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 Backdoor drops the following files:

  • %Windows%\PROPSYS.dll
  • %System%\imseo21.ime
  • %Windows%\Help\DirectX.msc
  • {Malware Path}\51FADBE.bat

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following processes:

  • C:\Windows\system32\Cacls.exe "C:\Windows\PROPSYS.dll" /E /G everyone:F
  • C:\Windows\system32\Cacls.exe "C:\Windows\system32\imseo21.ime" /E /G everyone:F
  • C:\Windows\system32\rundll32.exe "C:\Windows\system32\imseo21.ime",ProxyDll
  • cmd /c C:\Users\{BLOCKED}er_732\Desktop\51FADBE.bat

Other Details

This Backdoor connects to the following possibly malicious URL:

  • r2---sn-i3b7knld.{BLOCKED}1.com

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.444.04

FIRST VSAPI PATTERN DATE:

15 Aug 2018

VSAPI OPR PATTERN File:

14.445.00

VSAPI OPR PATTERN Date:

16 Aug 2018

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

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.  
  • %Windows%\PROPSYS.dll
  • %System%\imseo21.ime
  • %Windows%\Help\DirectX.msc
  • {Malware Path}\51FADBE.bat

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZXSHELL.WNZ. 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 the following Trend Micro Support pages for more information:


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