Analysis by: Jaime Benigno Reyes
 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.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Nov 2014

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.

Autostart Technique

This backdoor modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,{malware path}\{malware name},"

(Note: The default value data of the said registry entry is "%System%\userinit.exe,".)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://www.{BLOCKED}ye.co.jp/blog/2014/index.php
  • http://www.{BLOCKED}urin.or.jp/htm/copyright/folder/sc_flash/index.php
  • http://www.{BLOCKED}o-ton.com/koushi/detail/sc_flash/index.php

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.700
VSAPI OPR PATTERN File: 11.271.00
VSAPI OPR PATTERN Date: 12 Nov 2014

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

Scan your computer with your Trend Micro product and note files detected as BKDR_EMDIVI.SMA

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,{malware path}\{malware name},"
      To: Userinit = "%System%\userinit.exe,"

Step 6

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