BKDR_XTRAT.TNE


 ALIASES:

Trojan:Win32/Xtrat (Microsoft); RDN/Generic BackDoor!bcm (McAfee); W32.Extrat (Symantec); Trojan.Win32.Autoit.ema (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Autoit_c.BUKX (AVG)

 PLATFORM:

Windows

 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.

  TECHNICAL DETAILS

File Size:

589,824 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

12 May 2015

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 creates the following folders:

  • %User Temp%\IXP000.TMP
  • %System%\System

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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\RunOnce
wextract_cleanup0 = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 %User Temp%\IXP000.TMP\ "

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
System = "%System%\System\svchost.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
System = "%System%\System\svchost.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{YH40HP6C-7211-4OE3-2VWM-0IA3OF7W72QT}
StubPath = "%System%\System\svchost.exe restart"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
System = "%System%"

Other System Modifications

This backdoor deletes the following files:

  • %User Profile%\Windows\XmCfPV93kmoRP.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.)

It adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\XtremeRAT

HKEY_CURRENT_USER\SOFTWARE\XmCfPV93kmoRP

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{YH40HP6C-7211-4OE3-2VWM-0IA3OF7W72QT}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\XtremeRAT
Mutex = "XmCfPV93kmoRP"

HKEY_CURRENT_USER\Software\XmCfPV93kmoRP
ServerStarted = "30/03/2015 05:40:41"

HKEY_CURRENT_USER\Software\XmCfPV93kmoRP
ServerName = "%System%\System\svchost.exe"

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\IXP000.TMP\TMP4351$.TMP
  • %User Temp%\IXP000.TMP\Skype.exe
  • %System%\System\svchost.exe

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}0.1

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.750

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

[ Learn More ]

Step 3

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
    • XtremeRAT
  • In HKEY_CURRENT_USER\SOFTWARE
    • XmCfPV93kmoRP
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {YH40HP6C-7211-4OE3-2VWM-0IA3OF7W72QT}

Step 4

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\RunOnce
    • wextract_cleanup0 = "rundll32.exe %System%\advpack.dll,DelNodeRunDLL32 %User Temp%\IXP000.TMP\ "
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • System = "%System%\System\svchost.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • System = "%System%\System\svchost.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{YH40HP6C-7211-4OE3-2VWM-0IA3OF7W72QT}
    • StubPath = "%System%\System\svchost.exe restart"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • System = "%System%"
  • In HKEY_CURRENT_USER\Software\XtremeRAT
    • Mutex = "XmCfPV93kmoRP"
  • In HKEY_CURRENT_USER\Software\XmCfPV93kmoRP
    • ServerStarted = "30/03/2015 05:40:41"
  • In HKEY_CURRENT_USER\Software\XmCfPV93kmoRP
    • ServerName = "%System%\System\svchost.exe"

Step 5

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 Temp%\IXP000.TMP\TMP4351$.TMP
  • %User Temp%\IXP000.TMP\Skype.exe
  • %System%\System\svchost.exe

Step 6

Search and delete these folders

[ 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 Temp%\IXP000.TMP
  • %System%\System

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_XTRAT.TNE. 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%\Windows\XmCfPV93kmoRP.xtr


Did this description help? Tell us how we did.