TROJ_BHO.XL
Trojan:Win32/Chepdu.P (Microsoft); [000afaa8.EXE]:Cheppu (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Dpechu.a (v), Trojan.Win32.Dpechu.a (v) (Sunbelt); Gen:Trojan.Heur.VP.4q0@ammFUdmi (FSecure)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
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.
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\{4078CCAF-8646-3E2D-B409-8280BB025A60}
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
ctfmon.exe
HKEY_CLASSES_ROOT\D.1
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
D.1\CLSID
HKEY_CLASSES_ROOT\D
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
D\CLSID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}\ProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}\VersionIndependentProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}\InprocServer32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0\
FLAGS
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0\
0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0\
0\win32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0\
HELPDIR
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}\ProxyStubClsid
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}\ProxyStubClsid32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}\TypeLib
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{4078CCAF-8646-3E2D-B409-8280BB025A60}
IExplore = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
ctfmon.exe
Debugger = "%System%\ctfmon_kz.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}\InprocServer32
ThreadingModel = "Apartment"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}\TypeLib
Version = "1.0"
Dropping Routine
This Trojan drops the following files:
- %System%\xa42031.exe
- %System%\wr99360.dll
- %System%\ctfmon_kz.exe
- %System%\xa42281.exe
- %System%\xwr99360.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.)
This report is generated via an automated analysis system.
SOLUTION
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
Close all opened browser windows
Step 3
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
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
- ctfmon.exe
- In HKEY_CLASSES_ROOT
- D.1
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\D.1
- CLSID
- In HKEY_CLASSES_ROOT
- D
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\D
- CLSID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
- {4078CCAF-8646-3E2D-B409-8280BB025A60}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}
- ProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}
- VersionIndependentProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}
- InprocServer32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
- {270B9AFD-3053-3289-B7C4-16D2A582AB54}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}
- 1.0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0
- FLAGS
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0
- 0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0\0
- win32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{270B9AFD-3053-3289-B7C4-16D2A582AB54}\1.0
- HELPDIR
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
- {520697D6-9B28-31AD-8260-15C3EC83B6FB}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}
- ProxyStubClsid
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}
- ProxyStubClsid32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}
- TypeLib
Step 4
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{4078CCAF-8646-3E2D-B409-8280BB025A60}
- IExplore = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\ctfmon.exe
- Debugger = "%System%\ctfmon_kz.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{4078CCAF-8646-3E2D-B409-8280BB025A60}\InprocServer32
- ThreadingModel = "Apartment"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{520697D6-9B28-31AD-8260-15C3EC83B6FB}\TypeLib
- Version = "1.0"
Step 5
Search and delete these files
- %System%\xa42031.exe
- %System%\wr99360.dll
- %System%\ctfmon_kz.exe
- %System%\xa42281.exe
- %System%\xwr99360.dll
Step 6
Scan your computer with your Trend Micro product to delete files detected as TROJ_BHO.XL. 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.
Did this description help? Tell us how we did.