TROJ_DROPPER.UOU
Worm:Win32/Ainslot.A (Microsoft); Trojan-Dropper.Win32.Injector.czyk (Kaspersky)
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 modifies files, disabling programs and applications from properly running.
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:
- %User Profile%\Application Data\WinUpdate.exe
(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.)
It creates the following folders:
- %User Temp%\plugtemp
(Note: %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.)
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
WinUpdate = "%User Profile%\Application Data\WinUpdate.exe"
Other System Modifications
This Trojan modifies the following files:
- %Application Data%\GDIPFONTCACHEV1.DAT
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It deletes the following files:
- %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.608.45265
- %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.608.45312
- %User Profile%\v2.0.50727.42\security.config.cch.608.45500
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
SrvID\ID
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
INSTALL\DATE
It adds the following registry entries:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
SrvID\ID
6Z2603URHH = "Local"
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
INSTALL\DATE
6Z2603URHH = "March 7, 2012"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DoNotAllowExceptions = "0"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Temp%\plugtemp\svchost.exe = "%User Temp%\plugtemp\svchost.exe:*:Enabled:Windows Messanger"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Application Data\FreshGame.exe = "{random characters}"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
GDIPlus
FontCachePath = "%Application Data%"
(Note: The default value data of the said registry entry is %User Profile%\Local Settings\Application Data.)
Dropping Routine
This Trojan drops the following files:
- %User Profile%\Application Data\FreshGame.exe
- %User Temp%\plugtemp\svchost.exe
(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.. %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.)
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
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\SrvID
- ID
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\INSTALL
- DATE
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- WinUpdate = "%User Profile%\Application Data\WinUpdate.exe"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\SrvID\ID
- 6Z2603URHH = "Local"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\INSTALL\DATE
- 6Z2603URHH = "March 7, 2012"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
- DoNotAllowExceptions = "0"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %User Temp%\plugtemp\svchost.exe = "%User Temp%\plugtemp\svchost.exe:*:Enabled:Windows Messanger"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %User Profile%\Application Data\FreshGame.exe = "{random characters}"
Step 5
Restore this modified 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\GDIPlus
- From: FontCachePath = "%Application Data%"
To: FontCachePath = ""%User Profile%\Local Settings\Application Data""
- From: FontCachePath = "%Application Data%"
Step 6
Search and delete these files
- %User Profile%\Application Data\FreshGame.exe
- %User Temp%\plugtemp\svchost.exe
Step 7
Search and delete this folder
- %User Temp%\plugtemp
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DROPPER.UOU. 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 deleted/modified files and/or registry entries from backup
*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- %Application Data%\GDIPFONTCACHEV1.DAT
Step 10
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.
- %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.608.45265
- %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.608.45312
- %User Profile%\v2.0.50727.42\security.config.cch.608.45500
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