TROJ_DLOAD.EFF


 ALIASES:

PWS:Win32/OnLineGames.AH (Microsoft); W32.Gammima.AG (Symantec); Worm.Win32.AutoRun (fs) (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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:

209,408 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

22 Oct 2012

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.

Autostart Technique

This Trojan registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}

It 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\63577e33

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\1ffc4bb5

Other System Modifications

This Trojan deletes the following files:

  • %User Profile%\Cookies\index.dat
  • %System%\Drivers\EstRtw.sys
  • %Program Files%\Internet Explorer\ws2help.dll
  • %Program Files%\Internet Explorer\wshtcpip.dll

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

It adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\HOOK_ID

HKEY_CLASSES_ROOT\CLSID\SYS_DLL

HKEY_CLASSES_ROOT\IEHlprObj.IEHlprObj.1

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
IEHlprObj.IEHlprObj.1\CLSID

HKEY_CLASSES_ROOT\IEHlprObj.IEHlprObj

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
IEHlprObj.IEHlprObj\CurVer

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\VersionIndependentProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\Programmable

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\InprocServer32

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

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}\TypeLib

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\HOOK_ID
name = "{malware file name}"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\63577e33
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\63577e33
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\63577e33
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\63577e33
ImagePath = "\??\%System%\drivers\63577e33.sys"

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\1ffc4bb5
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\1ffc4bb5
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\1ffc4bb5
Start = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\1ffc4bb5
ImagePath = "\??\%System%\drivers\1ffc4bb5.sys"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}\TypeLib
Version = "1.0"

It deletes the following registry keys:

HKEY_CLASSES_ROOT\CLSID\TANG2_OTP

HKEY_CLASSES_ROOT\CLSID\SOS_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\System\CurrentControlSet\
Services\63577e33\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\63577e33\Security

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\1ffc4bb5\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\1ffc4bb5\Security

Dropping Routine

This Trojan drops the following files:

  • %System%\drivers\63577e33.sys
  • %System%\kakuzd.dll
  • %User Temp%\A1.zip
  • %User Temp%\B1.zip
  • %User Temp%\C1.zip
  • %User Temp%\Thq3.dll
  • %User Temp%\udH.dll
  • %System%\drivers\1ffc4bb5.sys
  • %System%\wshtcpzd.dll
  • %System%\wshtcpip.dll
  • %System%\midimap.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.155.229/xx/get.asp?{random characters}

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Close all opened browser windows

Step 4

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
    • 63577e33
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • 1ffc4bb5
  • In HKEY_CLASSES_ROOT\CLSID
    • HOOK_ID
  • In HKEY_CLASSES_ROOT\CLSID
    • SYS_DLL
  • In HKEY_CLASSES_ROOT
    • IEHlprObj.IEHlprObj.1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\IEHlprObj.IEHlprObj.1
    • CLSID
  • In HKEY_CLASSES_ROOT
    • IEHlprObj.IEHlprObj
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\IEHlprObj.IEHlprObj
    • CurVer
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {AB705622-B25B-491B-A6BF-4A46FDDBC88E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}
    • ProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}
    • VersionIndependentProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}
    • Programmable
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {AB705628-B25B-491B-A6BF-4A46FDDBC88E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{AB705628-B25B-491B-A6BF-4A46FDDBC88E}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {AB705621-B25B-491B-A6BF-4A46FDDBC88E}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}
    • TypeLib

Step 5

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 = "{malware file name}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\63577e33
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\63577e33
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\63577e33
    • Start = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\63577e33
    • ImagePath = "\??\%System%\drivers\63577e33.sys"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\SYS_DLL
    • name = "udH.dll"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\1ffc4bb5
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\1ffc4bb5
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\1ffc4bb5
    • Start = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\1ffc4bb5
    • ImagePath = "\??\%System%\drivers\1ffc4bb5.sys"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{AB705622-B25B-491B-A6BF-4A46FDDBC88E}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{AB705621-B25B-491B-A6BF-4A46FDDBC88E}\TypeLib
    • Version = "1.0"

Step 6

Search and delete these files

[ Learn More ]
There may be some component files 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.
  • %System%\drivers\63577e33.sys
  • %System%\kakuzd.dll
  • %User Temp%\A1.zip
  • %User Temp%\B1.zip
  • %User Temp%\C1.zip
  • %User Temp%\Thq3.dll
  • %User Temp%\udH.dll
  • %System%\drivers\1ffc4bb5.sys
  • %System%\wshtcpzd.dll
  • %System%\wshtcpip.dll
  • %System%\midimap.dll

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DLOAD.EFF. 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 8

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
  • %Program Files%\Internet Explorer\ws2help.dll
  • %Program Files%\Internet Explorer\wshtcpip.dll

Step 9

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
    • SOS_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\System\CurrentControlSet\Services\63577e33
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\63577e33
    • Security
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\1ffc4bb5
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\1ffc4bb5
    • Security


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