TROJ_ESTIWIR.E

September 05, 2014
 ALIASES:

Trojan:Win32/Estiwir (Microsoft); RDN/PWS-Mmorpg!le (McAfee); HEUR:Trojan.Win32.Generic (Kaspersky); Trojan-Dropper.Win32.OnlineGames.qcf (v) (Sunbelt); Win32/Heur (AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

739,797 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Sep 2014

Arrival Details

This Trojan 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 Trojan drops the following copies of itself into the affected system:

  • %User Temp%\15a6f.tmp

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

This Trojan registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\5f380c28

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\239339ae

Other System Modifications

This Trojan deletes the following files:

  • %User Profile%\Cookies\index.dat
  • %System%\Drivers\EstRtw.sys
  • %User Temp%\15e28.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\HOOK_ID

HKEY_CLASSES_ROOT\CLSID\SYS_DLL

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\HOOK_ID
name = "15e28.exe"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\5f380c28
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\5f380c28
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\5f380c28
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\5f380c28
ImagePath = "\??\%System%\drivers\5f380c28.sys"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\SYS_DLL
name = "eufuBwuwY.dll"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\239339ae
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\239339ae
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\239339ae
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\239339ae
ImagePath = "\??\%System%\drivers\239339ae.sys"

It deletes the following registry keys:

HKEY_CLASSES_ROOT\CLSID\TANG2_OTP

HKEY_CLASSES_ROOT\CLSID\HOK_OTP

HKEY_CLASSES_ROOT\CLSID\TANG1_NCP

HKEY_CLASSES_ROOT\CLSID\TANG1_URL

HKEY_CLASSES_ROOT\CLSID\AH3SEC

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\5f380c28\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\5f380c28\Security

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\239339ae\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\239339ae\Security

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\15e28.exe
  • %System%\drivers\5f380c28.sys
  • %System%\goodsb.dll
  • %User Temp%\A1.zip
  • %User Temp%\B1.zip
  • %User Temp%\C1.zip
  • %User Temp%\D1.zip
  • %User Temp%\DA6HdqAsu.dll
  • %User Temp%\eufuBwuwY.dll
  • %System%\drivers\239339ae.sys
  • %System%\ws2tcpip.dll

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://down.{BLOCKED}z.co.kr/updateV15/Position_Ver.html
  • http://down.{BLOCKED}z.co.kr/updateV15/_VER.html
  • http://{BLOCKED}4.25.178/post.asp?{random characters}

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • 5f380c28
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • 239339ae
  • In HKEY_CLASSES_ROOT\CLSID
    • HOOK_ID
  • In HKEY_CLASSES_ROOT\CLSID
    • SYS_DLL

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\HOOK_ID
    • name = "15e28.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\5f380c28
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\5f380c28
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\5f380c28
    • Start = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\5f380c28
    • ImagePath = "\??\%System%\drivers\5f380c28.sys"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\SYS_DLL
    • name = "eufuBwuwY.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\239339ae
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\239339ae
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\239339ae
    • Start = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\239339ae
    • ImagePath = "\??\%System%\drivers\239339ae.sys"

Step 5

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\15e28.exe
  • %System%\drivers\5f380c28.sys
  • %System%\goodsb.dll
  • %User Temp%\A1.zip
  • %User Temp%\B1.zip
  • %User Temp%\C1.zip
  • %User Temp%\D1.zip
  • %User Temp%\DA6HdqAsu.dll
  • %User Temp%\eufuBwuwY.dll
  • %System%\drivers\239339ae.sys
  • %System%\ws2tcpip.dll

Step 6

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

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\Cookies\index.dat
  • %System%\Drivers\EstRtw.sys
  • %User Temp%\15e28.exe

Step 8

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CLASSES_ROOT\CLSID
    • TANG2_OTP
  • In HKEY_CLASSES_ROOT\CLSID
    • HOK_OTP
  • In HKEY_CLASSES_ROOT\CLSID
    • TANG1_NCP
  • In HKEY_CLASSES_ROOT\CLSID
    • TANG1_URL
  • In HKEY_CLASSES_ROOT\CLSID
    • AH3SEC
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {18DF081C-E8AD-4283-A596-FA578C2EBDC3}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\5f380c28
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\5f380c28
    • Security
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\239339ae
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\239339ae
    • Security


Did this description help? Tell us how we did.