BKDR_XTRAT.SAD
Backdoor:Win32/Xtrat.A (Microsoft); RDN/Generic.dx!d2h (McAfee); W32.Extrat (Symantec); Troj/Agent-AGOO (Sophos); Trojan.Win32.Generic!BT (Sunbelt)
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.
It disables Task Manager, Registry Editor, and Folder Options.
It deletes itself after execution.
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.
Installation
This backdoor drops the following copies of itself into the affected system:
- %User Profile%\UpdaterWin\svhost.exe
(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.)
It creates the following folders:
- %User Profile%\Application Data\UpdaterWin
(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.)
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
UpdateWin = "%User Profile%\UpdaterWin\svhost.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
UpdateWin = "%User Profile%\UpdaterWin\svhost.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{1PDIF2EC-2V8E-O20K-8OQJ-57T3NVF1EN62}
StubPath = "%User Profile%\UpdaterWin\svhost.exe restart"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe %User Profile%\UpdaterWin\svhost.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\x4KybsbM
HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{1PDIF2EC-2V8E-O20K-8OQJ-57T3NVF1EN62}
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
It adds the following registry entries:
HKEY_CURRENT_USER\Software\x4KybsbM
ServerStarted = "4/2/2014 3:04:03 AM"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%User Profile%\UpdaterWin\svhost.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe %User Profile%\UpdaterWin\svhost.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
HKEY_CURRENT_USER\Software\x4KybsbM
InstalledServer = "%User Profile%\UpdaterWin\svhost.exe"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%User Profile%\UpdaterWin\svhost.exe"
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
Dropping Routine
This backdoor drops the following files:
- %User Profile%\Windows\x4KybsbM.cfg
- %User Profile%\Windows\x4KybsbM.xtr
(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.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://www.{BLOCKED}rmag.com/plugin.xtr
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
Identify and delete files detected as BKDR_XTRAT.SAD using either the Startup Disk or Recovery Console
Step 3
Enable Registry Editor, Task Manager, and Folder options
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_CURRENT_USER\SOFTWARE
- x4KybsbM
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
- {1PDIF2EC-2V8E-O20K-8OQJ-57T3NVF1EN62}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
- RunOnce
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
- Run
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
- Run
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\Microsoft\Windows\CurrentVersion\Run
- UpdateWin = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- UpdateWin = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{1PDIF2EC-2V8E-O20K-8OQJ-57T3NVF1EN62}
- StubPath = "%User Profile%\UpdaterWin\svhost.exe restart"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
- Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_CURRENT_USER\Software\x4KybsbM
- ServerStarted = "4/2/2014 3:04:03 AM"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
- Load = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
- Shell = "explorer.exe %User Profile%\UpdaterWin\svhost.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
- Microsoft = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_CURRENT_USER\Software\x4KybsbM
- InstalledServer = "%User Profile%\UpdaterWin\svhost.exe"
Step 6
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_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
- Load = "%User Profile%\UpdaterWin\svhost.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = "explorer.exe %User Profile%\UpdaterWin\svhost.exe"
To: Shell = ""Explorer.exe""
- From: Shell = "explorer.exe %User Profile%\UpdaterWin\svhost.exe"
Step 7
Search and delete these components
- %User Profile%\Windows\x4KybsbM.cfg
- %User Profile%\Windows\x4KybsbM.xtr
Step 8
Search and delete this folder
- %User Profile%\Application Data\UpdaterWin
Step 9
Scan your computer with your Trend Micro product to delete files detected as BKDR_XTRAT.SAD. 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.
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