Analysis by: Mar Philip Elaurza
ALIASES:

TrojanDropper:Win32/Zupdax.A!dha (Microsoft), Trojan.MulDrop5.46324 (DrWeb),

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 393,876 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Nov 2015

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.

Installation

This Trojan drops the following files:

  • %All Users%\updata\server.db
  • %All Users%\updata\McUtil.dll

It drops and executes the following files:

  • %All Users%\updata\winlogin.exe

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\XXZH

It adds the following registry entries:

HKEY_CURRENT_USER\Software\XXZH
key = 114225

HKEY_CURRENT_USER\Software\XXZH
load_path = {malware path}\{malware filename}.exe

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.136.06
FIRST VSAPI PATTERN DATE: 07 Nov 2015
VSAPI OPR PATTERN File: 12.137.00
VSAPI OPR PATTERN Date: 08 Nov 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

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

Restart in Safe Mode

[ Learn More ]

Step 4

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\XXZH
    • key = 114225
  • In HKEY_CURRENT_USER\Software\XXZH
    • load_path = {malware path}\{malware filename}.exe

Step 5

Delete this registry key

[ 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
    • XXZH

Step 6

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.  
  • %All Users%\updata\server.db
  • %All Users%\updata\McUtil.dll
  • %All Users%\updata\winlogin.exe

Step 7

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