ALIASES:

Trojan:Win32/Alureon.gen!E (Microsoft); Puper.gen.d (McAfee); Trojan.Zlob (Symantec); Trojan.Win32.DNSChanger.aqd (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse DNSChanger.M (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • 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.

  TECHNICAL DETAILS

File Size: 235,920 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 06 Jun 2013

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 creates the following folders:

  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nsx7.tmp
  • %Program Files%\ChristmasPorn
  • %System Root%\Documents and Settings\Wilbert
  • %Start Menu%\Programs\ChristmasPorn

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %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 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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\nsh1.tmp
  • %User Temp%\nsx7.tmp
  • %User Temp%\nsx7.tmp\nsF.tmp

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\ChristmasPorn

HKEY_CLASSES_ROOT\ChristmasPorn\CLSID

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
ChristmasPorn

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
ChristmasPorn
UninstallString = "%Program Files%\ChristmasPorn\Uninstall.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
ChristmasPorn
InstallLocation = "%Program Files%\ChristmasPorn"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
ChristmasPorn
DisplayName = "ChristmasPorn"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
ChristmasPorn
DisplayIcon = "%Program Files%\ChristmasPorn\Uninstall.exe,0"

HKEY_CURRENT_USER\Software\ChristmasPorn
Start Menu Folder = "ChristmasPorn"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{E13A8633-E77B-49D7-830C-ED5632B6883F}
NameServer = "85.255.113.110,85.255.112.104"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{E13A8633-E77B-49D7-830C-ED5632B6883F}
DhcpNameServer = "85.255.113.110,85.255.112.104"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
NameServer = "85.255.113.110,85.255.112.104"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
DhcpNameServer = "85.255.113.110,85.255.112.104"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
DhcpNameServer = "85.255.113.110 85.255.112.104"

(Note: The default value data of the said registry entry is 192.168.239.2.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
NameServer = "85.255.113.110 85.255.112.104"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
System = "kdtzn.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\notepad.exe.dat
  • %User Temp%\calc.exe.dat
  • %User Temp%\freebsd.exe.dat
  • %User Temp%\linux
  • %User Temp%\nsx7.tmp\DcryptDll.dll
  • %User Temp%\notepad.exe
  • %User Temp%\calc.exe
  • %User Temp%\freebsd.exe
  • %User Temp%\nsx7.tmp\nsExec.dll
  • %User Temp%\nsx7.tmp\modern-header.bmp
  • %Program Files%\ChristmasPorn\Uninstall.exe
  • %Start Menu%\Programs\ChristmasPorn\Uninstall.lnk
  • %User Temp%\nsx7.tmp\StartMenu.dll
  • %User Temp%\nsx7.tmp\nsF.tmp
  • %System%\kdtzn.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

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

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
    • ChristmasPorn
  • In HKEY_CLASSES_ROOT\ChristmasPorn
    • CLSID
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • ChristmasPorn

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ChristmasPorn
    • UninstallString = "%Program Files%\ChristmasPorn\Uninstall.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ChristmasPorn
    • InstallLocation = "%Program Files%\ChristmasPorn"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ChristmasPorn
    • DisplayName = "ChristmasPorn"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\ChristmasPorn
    • DisplayIcon = "%Program Files%\ChristmasPorn\Uninstall.exe,0"
  • In HKEY_CURRENT_USER\Software\ChristmasPorn
    • Start Menu Folder = "ChristmasPorn"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{E13A8633-E77B-49D7-830C-ED5632B6883F}
    • NameServer = "85.255.113.110,85.255.112.104"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{E13A8633-E77B-49D7-830C-ED5632B6883F}
    • DhcpNameServer = "85.255.113.110,85.255.112.104"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
    • NameServer = "85.255.113.110,85.255.112.104"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{706C9A23-9058-4780-9179-0EE8467AACB4}
    • DhcpNameServer = "85.255.113.110,85.255.112.104"

Step 4

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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • From: DhcpNameServer = "85.255.113.110 85.255.112.104"
      To: DhcpNameServer = ""192.168.239.2""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • NameServer = "85.255.113.110 85.255.112.104"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • System = "kdtzn.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%\notepad.exe.dat
  • %User Temp%\calc.exe.dat
  • %User Temp%\freebsd.exe.dat
  • %User Temp%\linux
  • %User Temp%\nsx7.tmp\DcryptDll.dll
  • %User Temp%\notepad.exe
  • %User Temp%\calc.exe
  • %User Temp%\freebsd.exe
  • %User Temp%\nsx7.tmp\nsExec.dll
  • %User Temp%\nsx7.tmp\modern-header.bmp
  • %Program Files%\ChristmasPorn\Uninstall.exe
  • %Start Menu%\Programs\ChristmasPorn\Uninstall.lnk
  • %User Temp%\nsx7.tmp\StartMenu.dll
  • %User Temp%\nsx7.tmp\nsF.tmp
  • %System%\kdtzn.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.
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nsx7.tmp
  • %Program Files%\ChristmasPorn
  • %System Root%\Documents and Settings\Wilbert
  • %Start Menu%\Programs\ChristmasPorn

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_ZLOB.HU. 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 Temp%\nsh1.tmp
  • %User Temp%\nsx7.tmp
  • %User Temp%\nsx7.tmp\nsF.tmp


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