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WORM_BUBLIK.NRK

January 25, 2013
 Analysis by: Rhena Inocencio
 ALIASES:

Backdoor:Win32/Caphaw.D (Microsoft), Trojan-Ransom.Win32.Foreign.ygc (Kaspersky), Trojan.Ransomlock.G (Symantec), Trj/OCJ.C (Panda)

 PLATFORM:

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

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Propagates via removable drives


This worm arrives via removable drives. 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. It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

380,928 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Jan 2013

Payload:

Collects system information, Steals information, Connects to URLs/IPs, Downloads files

Arrival Details

This worm arrives via removable drives.

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

  • %Application Data%\{random folder found}\{filename found in %System%}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following component file(s):

  • {removable drive letter}:\{random folder found}\$REChCLE.BIN - encrypted
  • {removable drive letter}:\{random folder found}\thLmbs.db - encrypted
  • {removable drive letter}:\{random folder found}\vagefile.sys - encrypted
  • {removable drive letter}:\{random folder found}\desktopfini - encrypted
  • {removable drive letter}:\{random folder found}\readme.tat - encrypted

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random CLSID} = "%Application Data%\{random folder found}\{filename found in %System%}.exe"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {drive letter}:\{random folder found}\{random filename}.{random extension}

Backdoor Routine

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

  • Remote Desktop / Remote Access
  • Download & Upload Files
  • Update And Uninstall self
  • Download and Load Additional Plugins
    >Disk Propagation (DiskSpread) - {Hostname}/files/010-update-rzwpbt9g/dsp.psd
    >Messenger Propagation (MessengerSpread)- {Hostname}/files/010-update-rzwpbt9g/msg.gsm
    >BackSocks - {Hostname}/files/010-update-rzwpbt9g/Bot.dll
    >ftpgrabber - {Hostname}/files/010-update-rzwpbt9g/ffile.dll
  • Redirect network traffic
  • Monitor Browser Activity

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

  • https://{BLOCKED}ections.cc/ping.html
  • https://{BLOCKED}s.su/ping.html
  • https://{BLOCKED}.su/ping.html
  • https://{BLOCKED}s.cc/ping.html
  • https://{BLOCKED}ections.su/ping.html
  • https://{BLOCKED}ctions.su/ping.html

Download Routine

This worm downloads an updated copy of itself from the following website(s):

  • {Hostname}/files/010-update-rzwpbt9g/usa_xcv.exe
  • https://{BLOCKED}.su/files/rar.exe

Information Theft

This worm gathers the following data:

  • Installed Applications
  • Directory and File List
  • Drive Informations
  • Network Information
  • Username
  • Computername
  • OS Version
  • Hardware Information
  • Running Processes

NOTES:

This worm creates .LNK (shortcut) files using folder names found in removable drives. It then hides the original folders tricking users to click .LNK files. This .LNK files point out to a dropped copy of itself in the removable drive using {random folder found in removable}\{random filename}.{random extension}.

  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

Scan your computer with your Trend Micro product and note files detected as WORM_BUBLIK.NRK

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 CLSID} = "%Application Data%\{random folder found}\{filename found in %System%}.exe"

Step 5

Search and delete these files

[ 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.
  • {removable drive letter}:\{random folder found}\$REChCLE.BIN
  • {removable drive letter}:\{random folder found}\thLmbs.db
  • {removable drive letter}:\{random folder found}\vagefile.sys
  • {removable drive letter}:\{random folder found}\desktopfini
  • {removable drive letter}:\{random folder found}\readme.tat

Step 6

Search and delete the file detected as WORM_BUBLIK.NRK

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files in the search result.

Step 7

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

NOTES:

Delete the .LNK files pointing to the malware using the file name of the malware you previously noted.

  1. Right click on a .LNK file then click Properties.
  2. Check the malware name in the target input box.
  3. If the target input box contains the malware name, select the file then press SHIFT+DELETE to delete it.

Unhide the folders by checking Show hidden files and folders in the Folder Options.


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