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BKDR_XTRAT.TNJ

July 12, 2015
 ALIASES:

Backdoor:Win32/Xtrat.A (Microsoft); Trojan.Gen.SMH (Symantec); Trojan.Win32.Xtrat.vvp (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse MSIL8.ZGH (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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

817,664 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

12 Jul 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 Profile%\Application Data\RuPD4NeO4WFY
  • %System%\InstallDir

(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.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This backdoor deletes the following files:

  • {malware path and file name}:zone.identifier
  • %User Profile%\Windows\arbhWQ6yo4eE.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\arbhWQ6yo4eE

It adds the following registry entries:

HKEY_CURRENT_USER\Software\XtremeRAT
Mutex = "arbhWQ6yo4eE"

HKEY_CURRENT_USER\Software\arbhWQ6yo4eE
ServerStarted = "11/06/2015 06:51:10"

Dropping Routine

This backdoor drops the following files:

  • %User Profile%\RuPD4NeO4WFY\429.xml
  • %User Startup%\UIuXmRYfc.lnk
  • %User Temp%\x.html
  • %System%\InstallDir\svchost.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.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %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

It deletes itself after execution.

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

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
    • arbhWQ6yo4eE

Step 3

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_CURRENT_USER\Software\XtremeRAT
    • Mutex = "arbhWQ6yo4eE"
  • In HKEY_CURRENT_USER\Software\arbhWQ6yo4eE
    • ServerStarted = "11/06/2015 06:51:10"

Step 4

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%\RuPD4NeO4WFY\429.xml
  • %User Startup%\UIuXmRYfc.lnk
  • %User Temp%\x.html
  • %System%\InstallDir\svchost.exe

Step 5

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 Profile%\Application Data\RuPD4NeO4WFY
  • %System%\InstallDir

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_XTRAT.TNJ. 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 7

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.

  • {malware path and file name}:zone.identifier
  • %User Profile%\Windows\arbhWQ6yo4eE.xtr


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