TROJ_GAMETHI.SDD
Worm:Win32/Taterf.B (Microsoft); Generic PWS.ak (McAfee); Trojan Horse (Symantec); HEUR:Trojan.Win32.Generic (Kaspersky); Mal/Taterf-B (Sophos); Worm.Win32.Taterf.b (v) (Sunbelt); Trojan horse SHeur2.BJEC (AVG)
Windows

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.
TECHNICAL DETAILS
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:
- %System%\bigdoor.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
bigsoft = "%System%\bigdoor.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\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
Other System Modifications
This Trojan deletes the following files:
- %System%\bigdoor.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
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\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\ProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\VersionIndependentProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\Programmable
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\InprocServer32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0\
FLAGS
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0\
0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0\
0\win32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0\
HELPDIR
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}\ProxyStubClsid
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}\ProxyStubClsid32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}\TypeLib
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\InprocServer32
ThreadingModel = "Apartment"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}\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.)
Dropping Routine
This Trojan drops the following files:
- %System%\bigmn0.dll
- %System%\bigie0.dll
- %System Root%\autorun.inf
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}6.com/1hg/ah1.rar
- {BLOCKED}0.1
This report is generated via an automated analysis system.
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
Restart in Safe Mode
Step 3
Close all opened browser windows
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_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
- {7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
- ProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
- VersionIndependentProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
- Programmable
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}
- InprocServer32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
- {7F235922-8F2C-4C08-83A8-BBE01BF9CC64}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}
- 1.0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0
- FLAGS
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0
- 0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0\0
- win32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{7F235922-8F2C-4C08-83A8-BBE01BF9CC64}\1.0
- HELPDIR
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
- {7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}
- ProxyStubClsid
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}
- ProxyStubClsid32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}
- TypeLib
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
- bigsoft = "%System%\bigdoor.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F23592B-8F2C-4C08-83A8-BBE01BF9CC64}\InprocServer32
- ThreadingModel = "Apartment"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{7F23592C-8F2C-4C08-83A8-BBE01BF9CC64}\TypeLib
- Version = "1.0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- 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 = ""2""
- 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"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
- From: NoDriveTypeAutoRun = "91"
To: NoDriveTypeAutoRun = ""91""
- From: NoDriveTypeAutoRun = "91"
Step 7
Search and delete these components
- %System%\bigmn0.dll
- %System%\bigie0.dll
- %System Root%\autorun.inf
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_GAMETHI.SDD. 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%\bigdoor.exe
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