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WORM_BUBLIK.GX
Aliases: Backdoor:Win32/Caphaw.D (Microsoft), Trojan-Ransom.Win32.Foreign.ybs (Kaspersky), a variant of Win32/Kryptik.ASIB trojan (Eset)
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet, Propagates via removable drives, Propagates via instant messaging applications

This malware spams messages to users using Skype in order to propagate. The spammed messages contain links that lead to an automatic download of the malware itself. This malware also has backdoor routines, which compromises an affected system's security.

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

For the related story, you may read the blog post Shylock Not the Lone Threat Targeting Skype

This worm 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.

It also has rootkit capabilities, which enables it to hide its processes and files from the user.

Technical Details


File size: 380,928 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 18 Jan 2013
Payload: Connects to URLs/IPs, Compromises system security

Arrival Details

This worm 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%}

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

It drops the following files:

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

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%}"

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 - {Hostname}/files/010-update-vl0d3/dsp.psd
       >Messenger Propagation - {Hostname}/files/010-update-vl0d3/msg.gsm
       >BackSocks - {Hostname}/files/010-update-vl0d3/Bot.dll
  • Redirect network traffic
  • Monitor Browser Activity

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

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

Rootkit Capabilities

This worm also has rootkit capabilities, which enables it to hide its processes and files from the user.

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 folder tricking users to click .LNK files. This .LNK files point out to a dropped copy of itself in the removable drive using a {random folder found in removable}\{random name}.{random extension}.

Solution


Minimum scan engine: 9.300
First VSAPI Pattern File: 9.662.09
First VSAPI Pattern Release Date: 18 Jan 2013
VSAPI OPR Pattern Version: 9.663.00
VSAPI OPR Pattern Release Date: 18 Jan 2013

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.GX

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%}"

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

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_BUBLIK.GX. 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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Analysis By: Mark Joseph Manahan

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