BKDR_EMDIVI.LEW

This malware is related to a cyberespionage campaign that uses an Ichitaro zero-day vulnerability, or the Multiple Ichitaro Products Unspecified Remote Code Execution Vulnerability (CVE-2014-7247)

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

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

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 other malware.

Installation

This backdoor drops and executes the following files:

• %User Temp%\vmwere.exe - also detected as BKDR_EMDIVI.LEW

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

It drops the following non-malicious files:

• %User Temp%\elec.doc - decoy file

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

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

• 59acb7e9073fbff85345f9e74f3f7f98

Autostart Technique

This backdoor drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:

• %All Users Startup%\wmwere.lnk - points to %User Temp%\vmwere.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

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:

• www.{BLOCKED}n.or.jp/htm/copyright/folder/index.php

Other Details

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

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

NOTES:

It 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 has a document icon and drops the non-malicious file elec.doc. It will then open the file elec.doc to deceive users that it is a normal file.