This malware is the payload of the exploit related to Sandworm zero-day vulnerability. The said vulnerability has been covered in MS14-060 and believed to be used in cyber attacks against European sectors and industries.
To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

This backdoor may be downloaded from remote sites by other malware.
It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.
Arrival Details
This backdoor may be downloaded from remote site(s) by the following malware:
Installation
This backdoor drops the following component file(s):
- %AppDataLocal%\FONTCACHE.DAT - detected as BKDR_BLACKEN.A
This is executed as follows:
rundll32.exe AppDataLocal%\FONTCACHE.DAT,MakeCache
(Note: %AppDataLocal% is the Application Data folder found in Local Settings, where it is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local 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.)
Autostart Technique
This backdoor drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:
- %User Startup%\{GUID}.lnk
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)
Other System Modifications
This backdoor adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = "no"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
DisableFirstRunCustomize = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\InformationBar
FirstTime = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\New Windows
PopupMgr = "no"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\PhishingFilter
Enabled = "0"
HKLM\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Cache
Persistent = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\TabbedBrowsing
WarnOnClose = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\TabbedBrowsing
WarnOnCloseAdvanced = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Recovery
NoReopenLastSession = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%System%\rundll32.exe = "DisableNXShowUI"
Backdoor Routine
This backdoor executes the following commands from a remote malicious user:
- Uninstall itself
- Load Plugin
- Unload Plugin
- Update config
- Download and execute arbitrary file
- Update DLL component
It connects to the following websites to send and receive information:
- {BLOCKED}5.{BLOCKED}3.193.131/{BLOCKED}c2VhdHJlaWRlczk0/dirconf/check.php
- sends the following: id={malware id}&bid={build id}=&nm={value}&cn={value}&num={value}
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
Remove the malware/grayware file that dropped/downloaded BKDR_BLACKEN.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)
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, Windows 7, and Windows Server 2008 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.
• For Windows 8, Windows 8.1, and Windows Server 2012 users
- Access the Charms bar by moving your mouse pointer to the upper right corner of the screen.
- Move your mouse pointer down and click Settings>Change your PC Settings.
- In the left panel, click General.
- In the right panel, scroll down to the bottom to find the Advanced startup section, then click the Restart now button and wait for the system to restart.
- In the Advanced Startup menu, click Troubleshoot>Advanced Options>Startup Settings>Restart and wait for the system to restart.
- In the Startup Settings menu, press 4 to enable safe mode.
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\Internet Explorer\Main
- Check_Associations = "no"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\InformationBar
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\New Windows
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\PhishingFilter
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Cache
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TabbedBrowsing
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TabbedBrowsing
- WarnOnCloseAdvanced = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- DisableFirstRunCustomize = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Recovery
- NoReopenLastSession = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- NoProtectedModeBanner = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
- %System%\rundll32.exe = "DisableNXShowUI"
To delete the registry value this malware/grayware created:
- Open Registry Editor.
» For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run, type regedit in the text box provided, and then press Enter.
» For Windows Vista, Windows 7, and Windows Server 2008 users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, and Windows Server 2012 users, right-click on the lower left corner of the screen, click Run, type regedit in the text box provided, and then press Enter. - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>Main - In the right panel, locate and delete the entry:
Check_Associations = "no" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>InformationBar - In the right panel, locate and delete the entry:
FirstTime = "0" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>New Windows - In the right panel, locate and delete the entry:
PopupMgr = "no" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>PhishingFilter - In the right panel, locate and delete the entry:
Enabled = "0" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows>CurrentVersion>Internet Settings>Cache - In the right panel, locate and delete the entry:
Persistent = "0" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>TabbedBrowsing - In the right panel, locate and delete the entry:
WarnOnClose = "0" - Again In the right panel, locate and delete the entry:
WarnOnCloseAdvanced = "0" - Again In the right panel, locate and delete the entry:
DisableFirstRunCustomize = "1" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Internet Explorer>Recovery - In the right panel, locate and delete the entry:
NoReopenLastSession = "1" - Again In the right panel, locate and delete the entry:
NoProtectedModeBanner = "1" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows NT>CurrentVersion>AppCompatFlags>Layers - In the right panel, locate and delete the entry:
%System%\rundll32.exe = "DisableNXShowUI" - Close Registry Editor.
Step 5
Search and delete this file
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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.
- %User Startup%\{GUID}.lnk
To manually delete a malware/grayware file from an affected system:
• For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click Start then click Search....
- In the File name* input box, type the following:
- %User Startup%\{GUID}.lnk
- In the Look In drop-down list, select My Computer then press Enter.
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).
• For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
- %User Startup%\{GUID}.lnk
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: Read the following Microsoft page if these steps do not work on Windows 7.
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_BLACKEN.A. 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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