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BKDR_KASIDET.XXRO

November 03, 2015
 Analysis by: David John Agni
 ALIASES:

Win32/Kasidet.AD (ESET-NOD32)

 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, Dropped by other malware


This malware is the payload for the Adobe Flash zero-day exploit (assigned with CVE-2015-7645) which is used in the cyberespionage campaign, Pawn Storm. In addition, the Angler Exploit Kit has reportedly integrated CVE-2015-7645.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

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.

  TECHNICAL DETAILS

File Size:

129,024 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Oct 2015

Payload:

Steals information, Displays message/message boxes, Compromises system security

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 drops the following files:

  • %Windows%\Tasks\WlVjY2kx.job
  • %Windows%\kernel32.dll
  • %Systems%\Tasks\WlVjY2kx

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

It drops the following copies of itself into the affected system:

  • %Application Data%\WlVjY2kx\{random filename}.exe

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

  • %Application Data%\WlVjY2kx\

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 mutexes to ensure that only one of its copies runs at any one time:

  • WlVjY2kx

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\Run
{random filename}.exe = "%Application Data%\WlVjY2kx\{random filename}.exe" ← (if user is Admin)

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random filename}.exe = "%Application Data%\WlVjY2kx\{random filename}.exe"

Backdoor Routine

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

  • Download and Install Plugin
  • Delete the registry key HKEY_CURRENT_USER\Software\WlVjY2kx\Addr
  • Download and Execute Files (.vbs, .dll)
  • Find Files and Process
  • Update itself
  • Uninstall itself
  • Modify the registry entries of HKEY_CURRENT_USER\Software\WlVjY2kx\rate
  • Performs DDOS attack
  • Log Keystrokes
  • Copy Clipboard

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}sco.biz/tasks.php
  • http://{BLOCKED}dspro.in/asks.php
  • http://{BLOCKED}pwr.pw/ks.php
  • http://{BLOCKED}azad.net/aks.php

As of this writing, the said sites are inaccessible.

Information Theft

This backdoor gathers the following data:

  • OS Version
  • Machine GUID
  • Installed AV Software

NOTES:

The variable {random file name} maybe svchost.exeor any .exe file that does not contain the following strings, found in the Windows folder:

  • install
  • setup
  • update
  • patch

It scans the memory of all running processes to get credit card data Track 1 and 2 except for the following processes:

  • [System]
  • smss.exe
  • csrss.exe
  • winlogon.exe
  • lsass.exe
  • spoolsv.exe
  • devenv.exe

It hooks Windows API of the following browsers or clients:

  • Firefox
  • Chrome
  • Internet Explorer
  • Debugger
  • Remote or Local Debugger

It terminates itself and displays an error message if any of the conditions are met:

  • If computer name contains the following strings:
    • MALTEST
    • TEQUILABOOMBOOM
    • SANDBOX
    • VIRUS
    • MALWARE
  • If path of the file contains the following strings:
    • SAMPLE
    • VIRUS
    • SANDBOX
  • If kernel32.dll exports the following function:
    • wine_get_unix_file_name
  • If any of the following registry keys are present:
    • HKEY_LOCAL_MACHINE\SOFTWARE\VMware, Inc.\VMware Tools
    • HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\VirtualBox Guest Additions
  • If the value of the following registry entry contains VMWARE, VBOX, or QEMU:
    • HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 0\Scsi Bus 0\Target Id 0\Logical Unit Id 0
      Identifier = {registry value}
  • If the value of the following registry entry contains VBOX, QEMU, or BOCHS:
    • HKEY_LOCAL_MACHINE\HARDWARE\Description\System
      SystemBiosVersion = {registry value}
  • If the value of the following registry entry contains VIRTUALBOX:
    • HKEY_LOCAL_MACHINE\HARDWARE\Description\System
      VideoBiosVersion = {registry value}

  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

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random filename}.exe = "%Application Data%\WlVjY2kx\{random filename}.exe"← (if user is Admin)
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random filename}.exe = "%Application Data%\WlVjY2kx\{random filename}.exe"

Step 5

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
    • WlVjY2kx

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.
  • %Application Data%\WlVjY2kx

Step 7

Search and delete this file

[ Learn More ]
There may be some files 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.
  • %Windows%\Tasks\WlVjY2kx.job
  • %Windows%\kernel32.dll
  • %Systems%\Tasks\WlVjY2kx

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_KASIDET.XXRO. 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.


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