Analysis by: Rika Joi Gregorio

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It 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.

  TECHNICAL DETAILS

File Size: 110,592 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 29 Oct 2014
Payload: Connects to URLs/IPs, Displays message/message boxes

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It 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:

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

(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)

It adds the following processes:

  • svchost.exe

It injects itself into the following processes running in the affected system's memory:

  • created svchost.exe

Autostart Technique

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

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

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\{random}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random}
{random} = "{hex value}"

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 URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.{BLOCKED}.223.115:443/index.php
  • http://{BLOCKED}.{BLOCKED}.82.99:8080/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

NOTES:

It display the following message in order to trick the users that the file wasn't able to execute.

It checks for running windows 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
  • PROCEXPL
  • PROCMON_WINDOW_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 it is running in a virtual machine:

  • AMIBI
  • PTLTD
  • Vbox
  • Virtual
  • VMware

It also checks if the following registry keys exist:

  • HARDWARE\ACPI\DSDT\AMIBI
  • HARDWARE\ACPI\DSDT\PTLTD__
  • HARDWARE\ACPI\DSDT\VBOX__
  • SYSTEM\CurrentControlSet\Enum\PCI\VEN_15AD&DEV_0774&SUBSYS_040515AD&REV_00
  • SYSTEM\CurrentControlSet\Enum\PCI\VEN_15AD&DEV_0774&SUBSYS_074015AD&REV_00
  • SYSTEM\CurrentControlSet\Enum\PCI\VEN_5333&DEV_8811&SUBSYS_00000000&REV_00
  • SYSTEM\CurrentControlSet\Enum\PCI\VEN_80EE&DEV_BEEF&SUBSYS_00000000&REV_00
  • SYSTEM\CurrentControlSet\Enum\PCI\VEN_80EE&DEV_CAFE&;SUBSYS_00000000&REV_00

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.256.05
FIRST VSAPI PATTERN DATE: 04 Nov 2014
VSAPI OPR PATTERN File: 11.257.00
VSAPI OPR PATTERN Date: 05 Nov 2014

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

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.WSEN. 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.

  • In HKEY_CURRENT_USER\Software
    • {random}


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