BKDR_EMDIVI.I
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
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.
It does not have any propagation routine.
It executes commands from a remote malicious user, effectively compromising the affected system.
It does not have any information-stealing capability.
TECHNICAL DETAILS
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 drops and executes the following files:
- %User Temp%\kptl.doc ← non-malicious file
- %User Temp%\leassaq.exe ← detected as BKDR_EMDIVI.I
(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:
- 9419a911dd211fba4fd81dd417ef3f47
Autostart Technique
This backdoor 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,.)
It drops the following file(s) in the Windows Startup folder to enable its automatic execution at every system startup:
- %Common Startup%\FlashUtil_ActiveX.lnk
- %User Startup%\FlashUtil_ActiveX.lnk
(Note: %Common Startup% is the system's shared Startup folder, which is usually C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003.. %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.)
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}kokan.jp/2008/12/home/index.php
- http://www.{BLOCKED}c.co.jp/view6/viewdata/book/index.php
Information Theft
This backdoor does not have any information-stealing capability.
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:
This backdoor enumerates all visible windows and compares each window's title bar text to the following strings:
- OLLYDBG
- PROCESS EXPLORER
- PROCESS HACKER
- PROCESS MONITOR
- SOFTICE
- W32DASM
- WIRESHARK
If a window's title bar text contains the said strings, it pauses the execution of its malicious routine by performing a Sleep command.
It does not have rootkit capabilities.
It does not exploit any vulnerability.
SOLUTION
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
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
- Userinit = "%System%\userinit.exe,{malware path}\{malware filename},"
- Userinit = "%System%\userinit.exe,{malware path}\{malware filename},"
Step 5
Search and delete these files
- %User Temp%\kptl.doc
- %User Temp%\leassaq.exe
- %Common Startup%\FlashUtil_ActiveX.lnk
- %User Startup%\FlashUtil_ActiveX.lnk
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_EMDIVI.I. 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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