Analysis by: Francis Xavier Antazo


Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)


  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


Infection Channel:

Downloaded from the Internet, Dropped by other malware

This malicious file is downloaded from cloaked URLs in spammed emails related to fake Viber applications

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 executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.


File Size:

159,744 bytes

File Type:


Memory Resident:


Initial Samples Received Date:

10 Nov 2014


Connects to URLs/IPs, Collects system information

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.

It may be downloaded from the following remote site(s):

  • http://{BLOCKED}hosting.biz.ht/object.php?vib=61+pbq2ZRacFdllkhKRYLw


This Backdoor drops the following copies of itself into the affected system and executes them:

  • %AppDataLocal%\{random file name}.exe

(Note: %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

It adds the following processes:

  • svchost.exe

It stays memory-resident by injecting codes into the following processes:

  • created svchost.exe

Autostart Technique

This Backdoor adds the following registry entries to enable its automatic execution at every system startup:

{random} = "%AppDataLocal%\{random file name}.exe"

Other System Modifications

This Backdoor adds the following registry keys:


It adds the following registry entries:

{random} = "{hex values}"

Backdoor Routine

This Backdoor executes the following commands from a remote malicious user:

  • Sleep/Idle
  • Download and execute arbitrary file
  • Uninstall itself
  • Download module and inject to svchost.exe
  • Update itself
  • Check latest malware version
  • Manage registry

It connects to the following websites to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.182.152:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.126.139:443/index.php
  • http://{BLOCKED}.{BLOCKED}.21.210:443/index.php
  • http://{BLOCKED}.{BLOCKED}.239.167:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.138.62:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.84.84:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.105.170:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.189.52:8080/index.php
  • http://{BLOCKED}.{BLOCKED}.147.192:8080/index.php

Information Theft

This Backdoor gathers the following data:

  • Malware version
  • Virtualization information
  • Running debugger/forensic tools
  • User name
  • Local IP address
  • Processor type
  • OS version
  • Antivirus product
  • Firewall product


This backdoor checks if there's a running window with the following names:

  • 99929D61-1338-48B1-9433-D42A1D94F0D2
  • 99929D61-1338-48B1-9433-D42A1D94F0D2-x32
  • 99929D61-1338-48B1-9433-D42A1D94F0D2-x64
  • APISpy32Class
  • Dumper
  • Dumper64
  • iptools.exe
  • Iris - Version 5.59
  • prl_cc.exe
  • prl_tools.exe
  • ProcessHacker
  • ProcessLasso_Notification_Class
  • SharedIntApp.exe
  • Tfrmrpcap
  • TSystemExplorerTrayForm.UnicodeClass
  • VBoxService.exe
  • VBoxTray.exe
  • vmsrvc.exe
  • vmtoolsd.exe
  • vmusrvc.exe
  • VMwareDragDetWndClass
  • VMwareSwitchUserControlClass
  • WdcWindow
  • wireshark.exe

It checks Service Disk or BIOS for the following registry information if under virtualization:

  • PRLS
  • Vbox
  • Virtual
  • VMware


Minimum Scan Engine:





12 Nov 2014

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random} = "%AppDataLocal%\{random file name}.exe"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_KULUOZ.VLU. 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 6

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • HKEY_CURRENT_USER\Software\{random}

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