BKDR_SHARK.AT
Trojan:Win32/Vinject.A (Microsoft); BackDoor-DKG.a (McAfee); Backdoor.Trojan (Symantec); Backdoor.Win32.Shark.fzt (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse BackDoor.Shark.F (AVG)
Windows 2000, Windows XP, Windows Server 2003

Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor 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 backdoor 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 backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
boredcoders = "%Windows%:Server.bat"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
boredcoders = "%Windows%:Server.bat"
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Setup\1765683
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{248DD896-BB45-11CF-9ABC-0080C7E7B78D}\Control
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{248DD890-BB45-11CF-9ABC-0080C7E7B78D}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{248DD890-BB45-11CF-9ABC-0080C7E7B78D}\1.0\
0
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Windows\Setup
It adds the following registry entries:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Setup\1765683
d = "À? 3B(?\_CHAR(0x10)_¼?NÐý?Åd"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{248DD896-BB45-11CF-9ABC-0080C7E7B78D}\InprocServer32
ThreadingModel = "Apartment"
(Note: The default value data of the said registry entry is Apartment.)
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{248DD892-BB45-11CF-9ABC-0080C7E7B78D}\TypeLib
Version = "1.0"
(Note: The default value data of the said registry entry is 1.0.)
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{248DD893-BB45-11CF-9ABC-0080C7E7B78D}\TypeLib
Version = "1.0"
(Note: The default value data of the said registry entry is 1.0.)
It deletes the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{248DD896-BB45-11CF-9ABC-0080C7E7B78D}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{248DD897-BB45-11CF-9ABC-0080C7E7B78D}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Dropping Routine
This backdoor drops the following files:
- %User Profile%\Application Data\kernel33.dll
- %Windows%:Server.bat
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)
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
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_CURRENT_USER\Software\VB and VBA Program Settings\Setup
- 1765683
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{248DD896-BB45-11CF-9ABC-0080C7E7B78D}
- Control
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
- {248DD890-BB45-11CF-9ABC-0080C7E7B78D}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{248DD890-BB45-11CF-9ABC-0080C7E7B78D}\1.0
- 0
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Windows
- Setup
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\Run
- boredcoders = "%Windows%:Server.bat"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- boredcoders = "%Windows%:Server.bat"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Setup\1765683
- d = "À? 3B(?\_CHAR(0x10)_¼?NÐý?Åd"
Step 5
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_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{248DD896-BB45-11CF-9ABC-0080C7E7B78D}\InprocServer32
- From: ThreadingModel = "Apartment"
To: ThreadingModel = ""Apartment""
- From: ThreadingModel = "Apartment"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{248DD892-BB45-11CF-9ABC-0080C7E7B78D}\TypeLib
- From: Version = "1.0"
To: Version = ""1.0""
- From: Version = "1.0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{248DD893-BB45-11CF-9ABC-0080C7E7B78D}\TypeLib
- From: Version = "1.0"
To: Version = ""1.0""
- From: Version = "1.0"
Step 6
Search and delete these components
- %User Profile%\Application Data\kernel33.dll
- %Windows%:Server.bat
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SHARK.AT. 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 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\SOFTWARE\Classes\CLSID
- {248DD896-BB45-11CF-9ABC-0080C7E7B78D}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
- {248DD897-BB45-11CF-9ABC-0080C7E7B78D}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
- Run
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
- Run
Did this description help? Tell us how we did.