TROJ_DROPPER.DSR
Worm.Win32.Taterf.b (v) (Sunbelt)
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.
It deletes itself after execution.
TECHNICAL DETAILS
174,592 bytes
EXE
Yes
13 Jun 2012
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\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
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\6825245b
Other System Modifications
This Trojan deletes the following files:
- %User Profile%\Cookies\index.dat
- %Program Files%\Internet Explorer\ws2help.dll
- %Program Files%\Internet Explorer\wshtcpip.dll
(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)
It adds the following registry keys:
HKEY_CLASSES_ROOT\CLSID\HOOK_ID
HKEY_CLASSES_ROOT\CLSID\SYS_DLL
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\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\ProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\VersionIndependentProgID
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\Programmable
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\InprocServer32
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0\
FLAGS
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0\
0
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0\
0\win32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0\
HELPDIR
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}\ProxyStubClsid
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}\ProxyStubClsid32
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}\TypeLib
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\HOOK_ID
name = "{malware file name}"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6825245b
Type = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6825245b
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6825245b
Start = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\6825245b
ImagePath = "\??\%System%\drivers\6825245b.sys"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\SYS_DLL
name = "TRC.dll"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\InprocServer32
ThreadingModel = "Apartment"
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}\TypeLib
Version = "1.0"
It deletes the following registry keys:
HKEY_CLASSES_ROOT\CLSID\TANG2_OTP
HKEY_CLASSES_ROOT\CLSID\SOS_OTP
HKEY_CLASSES_ROOT\CLSID\TANG1_NCP
HKEY_CLASSES_ROOT\CLSID\TANG1_URL
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{18DF081C-E8AD-4283-A596-FA578C2EBDC3}
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\6825245b\Enum
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\6825245b\Security
Dropping Routine
This Trojan drops the following files:
- %System%\drivers\6825245b.sys
- %System%\Softitm.dll
- %User Temp%\A1.zip
- %User Temp%\B1.zip
- %User Temp%\hfgsuEhU.dll
- %User Temp%\TRC.dll
- %System%\wshtcpit.dll
- %System%\wshtcpip.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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://get.{BLOCKED}x.com/xx/get.asp?{random characters}
It deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.200
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
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_LOCAL_MACHINE\System\CurrentControlSet\Services
- 6825245b
- In HKEY_CLASSES_ROOT\CLSID
- HOOK_ID
- In HKEY_CLASSES_ROOT\CLSID
- SYS_DLL
- 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
- {CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
- ProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
- VersionIndependentProgID
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
- Programmable
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}
- InprocServer32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
- Browser Helper Objects
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib
- {CC0F01F8-1C87-418C-AC9D-E04BF946BB11}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}
- 1.0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0
- FLAGS
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0
- 0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0\0
- win32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\TypeLib\{CC0F01F8-1C87-418C-AC9D-E04BF946BB11}\1.0
- HELPDIR
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface
- {CC0F01F1-1C87-418C-AC9D-E04BF946BB11}
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}
- ProxyStubClsid
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}
- ProxyStubClsid32
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}
- 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_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\HOOK_ID
- name = "{malware file name}"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6825245b
- Type = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6825245b
- ErrorControl = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6825245b
- Start = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\6825245b
- ImagePath = "\??\%System%\drivers\6825245b.sys"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\SYS_DLL
- name = "TRC.dll"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{CC0F01F2-1C87-418C-AC9D-E04BF946BB11}\InprocServer32
- ThreadingModel = "Apartment"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{CC0F01F1-1C87-418C-AC9D-E04BF946BB11}\TypeLib
- Version = "1.0"
Step 6
Search and delete these files
- %System%\drivers\6825245b.sys
- %System%\Softitm.dll
- %User Temp%\A1.zip
- %User Temp%\B1.zip
- %User Temp%\hfgsuEhU.dll
- %User Temp%\TRC.dll
- %System%\wshtcpit.dll
- %System%\wshtcpip.dll
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER.DSR. 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 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.
- %User Profile%\Cookies\index.dat
- %Program Files%\Internet Explorer\ws2help.dll
- %Program Files%\Internet Explorer\wshtcpip.dll
Step 9
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_CLASSES_ROOT\CLSID
- TANG2_OTP
- In HKEY_CLASSES_ROOT\CLSID
- SOS_OTP
- In HKEY_CLASSES_ROOT\CLSID
- TANG1_NCP
- In HKEY_CLASSES_ROOT\CLSID
- TANG1_URL
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
- {18DF081C-E8AD-4283-A596-FA578C2EBDC3}
- In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\6825245b
- Enum
- In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\6825245b
- Security
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