TROJ_DROPPR.TRWI
Trojan:Win32/Dynamer!ac (Microsoft); [00005240.EXE]:RDN/Downloader.a!sm (McAfee); Trojan Horse (Symantec); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Downloader.Agent2.BVAX.dropper (AVG)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/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
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 creates the following folders:
- %Program Files%\Common Files\Plugins
(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)
Autostart Technique
This Trojan 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\wfthserv\Parameters
Other System Modifications
This Trojan deletes the following files:
- %Temp%\scs9.tmp
- %Temp%\scsC.tmp
(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
wfthserv = "wfthserv,!WIFI Support Service"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
Description = "WIFI Support Service"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
DisplayName = "WIFI Support Service"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
Group = "Com Infrastructure"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
ObjectName = "LocalSystem"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
Start = "2"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
Type = "1"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
FailureAction = "{random values}"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv
ImagePath = "%SystemRoot%\system32\svchost -k wfthserv"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wfthserv\Parameters
ServiceDll = "%System%\wfthserv32.dll"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DataAccess
ppp = "{malware path and file name}"
Dropping Routine
This Trojan drops the following files:
- %System%\wfthserv32.dll
- %Program Files%\Common Files\Plugins\iconfig.txt
- %Program Files%\Common Files\Plugins\bbb.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://werfdasfxcv.{BLOCKED}n.com/iconfig.txt
- http://werfdasfxcv.{BLOCKED}n.com/bbb.exe
- {BLOCKED}.42.19
- {BLOCKED}.87.123
It deletes itself after execution.
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wfthserv
- Parameters
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 NT\CurrentVersion\SvcHost
- wfthserv = "wfthserv,!WIFI Support Service"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- Description = "WIFI Support Service"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- DisplayName = "WIFI Support Service"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- ErrorControl = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- Group = "Com Infrastructure"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- ObjectName = "LocalSystem"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- Start = "2"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- Type = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- FailureAction = "{random values}"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv
- ImagePath = "%SystemRoot%\system32\svchost -k wfthserv"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wfthserv\Parameters
- ServiceDll = "%System%\wfthserv32.dll"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DataAccess
- ppp = "{malware path and file name}"
Step 5
Search and delete these components
- %System%\wfthserv32.dll
- %Program Files%\Common Files\Plugins\iconfig.txt
- %Program Files%\Common Files\Plugins\bbb.exe
Step 6
Search and delete this folder
- %Program Files%\Common Files\Plugins
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPR.TRWI. 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.
- %Temp%\scs9.tmp
- %Temp%\scsC.tmp
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