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BKDR_EMDIVI.AB

January 28, 2015
 Modified by: Jaime Benigno Reyes
 ALIASES:

Trojan:Win32/Xabil.A (Micrtosoft)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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. It may be dropped by other malware.

It does not have any propagation routine.

It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

215,040 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Jan 2015

Payload:

Connects to URLs/IPs

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.

It may be dropped by the following malware:

  • TROJ_XABIL.JUI

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • fd681ad714d8f08f357487df1cf9b8e1

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,".)

Propagation

This backdoor does not have any propagation routine.

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Enumerate files and folders
  • Delete files and folders
  • Download files
  • Upload files
  • Execute files
  • Get file attributes
  • Enumerate processes
  • Perform remote shell
  • Loads a library using LoadLibrary API
  • Import functions from a library using GetProcAddress API
  • Gather credentials using CredEnumerate or PStoreCreateInstance API
  • Gather Firefox settings from prefs.js
  • Gather proxy settings from proxy.pac
  • Gather proxy settings from windows registry
  • Sleep

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://www.{BLOCKED}d.gr.jp/100.html
  • http://www.{BLOCKED}ai.com/images/fuck/index.php
  • http://www.{BLOCKED}anti.com/shinyo/backup/look/index.php
  • http://www.{BLOCKED}norei.com/blog/index.php
  • http://www.{BLOCKED}ld.co.jp/tenpo/look/index.php

As of this writing, the said sites are inaccessible.

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

  • http://www.microsoft.com
  • http://www.msftncsi.com
  • http://www.yahoo.co.jp

NOTES:

This backdoor enumerates all visible windows and compares each window's title bar text with the following strings:

  • Ollydbg
  • Process Explorer
  • Process Hacker
  • Process Monitor
  • SoftICE
  • W32Dasm
  • WireShark

If a window's title bar text contains any of the said strings, it will pause the execution of its malicious routine by performing a Sleep command.

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.438.02

FIRST VSAPI PATTERN DATE:

26 Jan 2015

VSAPI OPR PATTERN File:

11.439.00

VSAPI OPR PATTERN Date:

27 Jan 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

Remove malware/grayware files that dropped/downloaded BKDR_EMDIVI.AB. (Note: Please skip this step if the threats listed below have already been removed.)

    • TROJ_XABIL.JUI

Step 4

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

Step 5

Restart in Safe Mode

[ Learn More ]

Step 6

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 7

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