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.
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}.
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
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To restart in Safe Mode:
• For Windows 2000 users
- Restart your computer.
- Press F8 when you see the Starting Windows bar at the bottom of the screen.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows XP users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Windows Advanced Options menu does not appear, try restarting then pressing F8 several times when the POST screen appears.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows Server 2003 users
- Restart your computer.
- Press F8 after Windows starts up. If the Windows Advanced Options menu does not appear, try restarting again and pressing F8 several times afterward.
- On the Windows Advanced Option menu, use the arrow keys to select Safe Mode then press Enter.
• For Windows Vista and Windows 7 users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.
- On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.
Step 4
Delete this registry value
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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%}"
To delete the registry value this malware/grayware created:
- Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
- In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
{random CLSID} = "%Application Data%\{random folder found}\{filename found in %System%}" - Close Registry Editor.
Step 5
Search and delete these files
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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
To delete malware/grayware files:
- Search for 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
Note: To do a search for the following files, right-click Start then click Search... or Find..., depending on the version of Windows you are running. For each file to be deleted, type its file name in the Named input box. In the Look In drop-down list, select My Computer, then press Enter. - Once located, select the file then press SHIFT+DELETE to permanently delete the file.
- Repeat the said steps for all files listed.
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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