WORM_LINEAGE.DDW


 ALIASES:

Worm:Win32/Taterf.B (Microsoft); Generic PWS.ak (McAfee); W32.Gammima (Symantec); Packed.Win32.Krap.g (Kaspersky); Worm.Win32.Taterf.b (v) (Sunbelt); Win32/Heur (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

  TECHNICAL DETAILS

File Size:

176,128 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Apr 2013

Arrival Details

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

  • %System%\kvosoft.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
kvasoft = "%System%\kvosoft.exe"

It 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\{CE7C3CF0-4B15-11D1-ABED-709549C10000}

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\KAVsys

Other System Modifications

This worm deletes the following files:

  • %System Root%\6asmuyut.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

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\{CE7C3CF0-4B15-11D1-ABED-709549C10000}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\VersionIndependentProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\Programmable

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\InprocServer32

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

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0\
0

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0\
0\win32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}\ProxyStubClsid

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}\ProxyStubClsid32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}\TypeLib

It adds the following registry entries:

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

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

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\KAVsys
ImagePath = "\??\%System%\drivers\klif.sys"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\InprocServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}\TypeLib
Version = "1.0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "0"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoDriveTypeAutoRun = "91"

(Note: The default value data of the said registry entry is 91.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\KAVsys\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\KAVsys\Security

Dropping Routine

This worm drops the following files:

  • %System%\drivers\klif.sys
  • %System%\hgkjghg0.dll
  • %System%\dsetwem0.dll
  • %System Root%\autorun.inf
  • %System Root%\6asmuyut.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}k.com/xhg2/ll1.rar

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

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
    • KAVsys
  • 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
    • {CE7C3CF0-4B15-11D1-ABED-709549C10000}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}
    • ProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}
    • VersionIndependentProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}
    • Programmable
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
    • {CE7C3CE2-4B15-11D1-ABED-709549C10000}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}
    • 1.0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0
    • FLAGS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0
    • 0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0\0
    • win32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CE7C3CE2-4B15-11D1-ABED-709549C10000}\1.0
    • HELPDIR
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
    • {CE7C3CEF-4B15-11D1-ABED-709549C10000}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}
    • ProxyStubClsid
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}
    • ProxyStubClsid32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}
    • 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • kvasoft = "%System%\kvosoft.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KAVsys
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KAVsys
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KAVsys
    • Start = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\KAVsys
    • ImagePath = "\??\%System%\drivers\klif.sys"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\InprocServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CE7C3CEF-4B15-11D1-ABED-709549C10000}\TypeLib
    • Version = "1.0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"

Step 6

Restore these modified registry values

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = ""2""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "0"
      To: CheckedValue = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • From: NoDriveTypeAutoRun = "91"
      To: NoDriveTypeAutoRun = ""91""

Step 7

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.
  • %System%\drivers\klif.sys
  • %System%\hgkjghg0.dll
  • %System%\dsetwem0.dll
  • %System Root%\autorun.inf
  • %System Root%\6asmuyut.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_LINEAGE.DDW. 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 9

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.

  • %System Root%\6asmuyut.exe

Step 10

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_LOCAL_MACHINE\System\CurrentControlSet\Services\KAVsys
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\KAVsys
    • Security


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