BKDR_EMDIVI.F
HEUR:Trojan.Win32.Generic(Kaspersky),a variant of Win32/Agent.WGN(NOD32)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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 does not have any propagation routine.
It executes commands from a remote malicious user, effectively compromising the affected system.
TECHNICAL DETAILS
203,776 bytes
EXE
Yes
01 Oct 2014
Executes files
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 adds the following mutexes to ensure that only one of its copies runs at any one time:
- 9419a911dd211fba4fd81dd417ef3f47
Autostart Technique
This backdoor drops the following shortcut pointing to its copy in the User Startup folder to enable its automatic execution at every system startup:
- %ProgramData%\Microsoft\Windows\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows 7 and Vista)
- %User Startup%\FlashUtil_ActiveX.lnk-lnk to the malware(Windows XP)
- %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows 7 and Vista)
- %All Users Profile%\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows XP)
(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,{malware path}\{malware filename},"
(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}.{BLOCKED}a.gr.jp/info/yougo/book/index.php
- http://www.{BLOCKED}c.{BLOCKED}o.jp/view6/viewdata/book/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
- W32Dasm
- WireShark
- SoftICE
- Process Explorer
- Process Monitor
- Process Hacker
If a window's title bar text contains 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
9.700
11.182.03
30 Sep 2014
11.183.00
01 Oct 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
Identify and delete files detected as BKDR_EMDIVI.F using either the Startup Disk or Recovery Console
Step 4
Restore these modified registry values
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 filename},"
To: Userinit = %System%\userinit.exe,
- From: Userinit = "%System%\userinit.exe,{malware path}\{malware filename},"
Step 5
Search and delete these files
- %ProgramData%\Microsoft\Windows\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows 7 and Vista)
- %User Startup%\FlashUtil_ActiveX.lnk-lnk to the malware(Windows XP)
- %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows 7 and Vista)
- %All Users Profile%\Start Menu\Programs\Startup\FlashUtil_ActiveX.lnk-lnk to the malware(Windows XP)
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_EMDIVI.F. 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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