WORM_AUTORUN.BWH
Worm:Win32/Taterf.B (Microsoft); PWS-Gamania.gen.a (McAfee); W32.Gammima.AG (Symantec); Packed.Win32.Krap.b (Kaspersky); Mal/EncPk-DH (Sophos); Packed.Win32.Krap.b (v) (Sunbelt); Trojan horse PSW.OnlineGames.AO (AVG)
Windows
![](/vinfo/imgFiles/legend.jpg)
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
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%\kxvo.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
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
kxva = "%System%\kxvo.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}
Other System Modifications
This worm adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
IEHlprObj.IEHlprObj.1\CLSID
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_CLASSES_ROOT\IEHlprObj.IEHlprObj
HKEY_CLASSES_ROOT\IEHlprObj.IEHlprObj.1
HKEY_CLASSES_ROOT\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}
HKEY_CLASSES_ROOT\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\
InprocServer32
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\InprocServer32
ThreadingModel = "Apartment"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\InprocServer32
(Defualt) = "%System%\ieso0.dll"
HKEY_CLASSES_ROOT\CLSID\{CE7C3CF0-4B15-11D1-ABED-709549C10000}\
InprocServer32
(Default) = "%System%\ieso0.dll"
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 1.)
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.)
Dropping Routine
This worm drops the following files:
- %User Temp%\ro45z.dll
- %System%\ieso0.dll
- %System%\fool0.dll
(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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Other Details
This worm connects to the following possibly malicious URL:
- http://www.{BLOCKED}0.com/hg2/ll.rar
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
Delete this registry key
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\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
- {CE7C3CF0-4B15-11D1-ABED-709549C10000}
- {CE7C3CF0-4B15-11D1-ABED-709549C10000}
- In HKEY_CLASSES_ROOT
- IEHlprObj.IEHlprObj
- IEHlprObj.IEHlprObj
- In HKEY_CLASSES_ROOT
- IEHlprObj.IEHlprObj1
- IEHlprObj.IEHlprObj1
- In HKEY_CLASSES_ROOT\CLSID
- {CE7C3CF0-4B15-11D1-ABED-709549C10000}
- {CE7C3CF0-4B15-11D1-ABED-709549C10000}
Step 5
Delete this registry value
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
- kxva = "%System%\kxvo.exe"
- kxva = "%System%\kxvo.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- ShowSuperHidden = "0"
- ShowSuperHidden = "0"
Step 6
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = "2"
To: Hidden = 1
- From: Hidden = "2"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
- From: CheckedValue = "0"
To: CheckedValue = 1
- From: CheckedValue = "0"
Step 7
Search and delete these components
- %User Temp%\ro45z.dll
- %System%\ieso0.dll
- %System%\fool0.dll
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_AUTORUN.BWH. 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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