BKDR_XTRAT.SAD


 ALIASES:

Backdoor:Win32/Xtrat.A (Microsoft); RDN/Generic.dx!d2h (McAfee); W32.Extrat (Symantec); Troj/Agent-AGOO (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • 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

File Size:

179,536 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Apr 2014

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

Minimum Scan Engine:

9.300

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

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

Step 4

Delete this registry key

[ Learn More ]

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

[ Learn More ]

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

[ Learn More ]

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""

Step 7

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Profile%\Windows\x4KybsbM.cfg
  • %User Profile%\Windows\x4KybsbM.xtr

Step 8

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %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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