BKDR_SHIBOT.X

November 26, 2014
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Backdoor:Win32/IRCbot.HI (Microsoft)

 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:

Dropped by other malware, Downloaded from the Internet

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:

50,176 bytes

File Type:

EXE

File Compression:

UPX

Memory Resident:

Yes

Initial Samples Received Date:

21 Nov 2014

Payload:

Downloads files, Terminates processes, 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 copies of itself into the affected system:

  • {folder options 1}\{file name}
  • {folder options 2}\{random numbers}\{file name}

It creates the following folders:

  • {folder options 2}\{random numbers}

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • MAIN_{random numbers}
  • BACKUP_{random numbers}
  • UNINSTALL_{random numbers}

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\RunOnce
{random numbers} = {folder options 2}\{random numbers}\{file name}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
{random numbers} = {folder options 2}\{random numbers}\{file name}

Other System Modifications

This backdoor deletes the following files:

  • {folder options 2}\{random numbers}\{file name}:Zone.Identifier
  • {malware path and file name}:zone.identifier

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoWindowsUpdate = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

(Note: The default value data of the said registry entry is 1.)

Backdoor Routine

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

  • Download arbitrary files
  • Update itself
  • Perform remote shell
  • Perform DDoS
  • Perform basic IRC commands
  • Initialize Skype for backdoor routines
  • Visit arbitrary websites
  • Uninstall itself

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

  • http://www.{BLOCKED}asla.ru/ath/gate.php

It posts the following information to its command and control (C&C) server:

  • Memory (RAM) usage
  • Unique session/victim ID
  • Processor information
  • Operating system information
  • Status of backdoor routines issued

Download Routine

This backdoor downloads updated copies of itself from the following websites:

  • http://www.{BLOCKED}asla.ru/ath/sploit/natmasla.exe

NOTES:

Where {folder options 1} can be any of the following:

  • %User Temp%
  • %User Profile%
  • %AllUsersProfile%
  • %AllUsersProfile%\Start Menu\Programs\Startup - for Windows XP
  • %ProgramData%
  • %ProgramData%\Microsoft\Windows\Start Menu\Programs\Startup - for Windows 7 and later
  • %User Startup%

{folder options 2} can be any of the following:

  • %Application Data%\{random numbers}
  • %Windows%\{random numbers}

{file name} can be any of the following:

  • svchost
  • csrss
  • xblstat
  • winlogon
  • smss
  • taskhost
  • unsecapp
  • AdobeARM
  • winsys
  • jusched
  • BCU
  • wscntfy
  • conhost
  • csrss
  • dwm
  • sidebar
  • ADService
  • AppServices
  • acrotray
  • ctfmon
  • lsass
  • realsched
  • spoolsv

It terminates itself if found running under the following Sandbox environments:

  • Sandboxie
  • JoeBox
  • CWSandbox

It terminates itself the following antivirus software is found running in the system:

  • Avast

  SOLUTION

Minimum Scan Engine:

9.700

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

Restart in Safe Mode

[ Learn More ]

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\Microsoft\Windows\CurrentVersion\RunOnce
    • {random numbers} = {folder options 2}\{random numbers}\{file name}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    • {random numbers} = {folder options 2}\{random numbers}\{file name}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • NoFolderOptions = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • NoWindowsUpdate = "1"

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: ShowSuperHidden = "0"
      To: ShowSuperHidden = 1

Step 5

Search and delete this folder

[ 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.
  • {folder options 2}\{random numbers}

Step 6

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