Arrival Details
This Trojan 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 Trojan drops the following copies of itself into the affected system:
- %User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
It creates the following folders:
- %User Profile%\Application Data\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\Printers\Defaults\
{65BC7B10-FA64-60C3-D618-4F89B601C075}
HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\
Microsoft\Windows\CurrentVersion\
RunOnce
It adds the following registry entries:
HKEY_CURRENT_USER\Printers\Defaults\
{65BC7B10-FA64-60C3-D618-4F89B601C075}
Component_01 = "{random values}"
HKEY_CURRENT_USER\Printers\Defaults\
{65BC7B10-FA64-60C3-D618-4F89B601C075}
Component_00 = "{random values}"
HKEY_CURRENT_USER\Software\Microsoft\
Command Processor
AutoRun = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
It modifies the following registry entries:
HKEY_CURRENT_USER\Control Panel\Desktop
SCRNSAVE.EXE = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
(Note: The default value data of the said registry entry is %Windows%\system32\logon.scr.)
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
Run = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
Dropping Routine
This Trojan drops the following files:
- %User Startup%\hostname.lnk
(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)
Other Details
This Trojan connects to the following possibly malicious URL:
- http://{BLOCKED}o.io/json
- {BLOCKED}.194
It deletes itself after execution.
This report is generated via an automated analysis system.
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
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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 3
Enable Registry Editor, Task Manager, and Folder options
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By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.
To enable Registry Editor, Task Manager, and Folder options:
- Open Notepad. To do this:
- For Windows 2000, XP, and Server 2003 users:
Click Start>Run, type Notepad in the text box provided, then press Enter. - For Windows Vista, 7, and Server 2008 users:
Click start. Type Notepad , then press Enter. - For Windows 8, 8.1, and 2012 users:
Right-click on the lower left corner of the screen. Click Run. Type Notepad in the input field, then press Enter.
- Copy and paste the following script:
- Save this file as C:\RESTORE.VBS.
- Run C:\RESTORE.VBS by double-clicking on the file.
- Click Yes at the prompt of the message box to execute the .VBS file.
Step 4
Delete this registry key
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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\Printers\Defaults
- {65BC7B10-FA64-60C3-D618-4F89B601C075}
- In HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\Microsoft\Windows\CurrentVersion
To delete the registry key 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>Printers>Defaults - Still in the left panel, locate and delete the key:
{65BC7B10-FA64-60C3-D618-4F89B601C075} - In the left panel, double-click the following:
HKEY_USERS>S-1-5-21-1645522239-1292428093-682003330-1003>Software>Microsoft>Windows>CurrentVersion - Still in the left panel, locate and delete the key:
RunOnce - Close Registry Editor.
Step 5
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
- hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
- hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
- In HKEY_CURRENT_USER\Printers\Defaults\{65BC7B10-FA64-60C3-D618-4F89B601C075}
- Component_01 = "{random values}"
- In HKEY_CURRENT_USER\Printers\Defaults\{65BC7B10-FA64-60C3-D618-4F89B601C075}
- Component_00 = "{random values}"
- In HKEY_CURRENT_USER\Software\Microsoft\Command Processor
- AutoRun = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
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>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe " - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>RunOnce - In the right panel, locate and delete the entry:
hostname = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe " - In the left panel, double-click the following:
HKEY_CURRENT_USER>Printers>Defaults>{65BC7B10-FA64-60C3-D618-4F89B601C075} - In the right panel, locate and delete the entry:
Component_01 = "{random values}" - Again In the right panel, locate and delete the entry:
Component_00 = "{random values}" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Command Processor - In the right panel, locate and delete the entry:
AutoRun = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe " - Close Registry Editor.
Step 6
Restore these modified registry values
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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\Control Panel\Desktop
- From: SCRNSAVE.EXE = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe "
To: SCRNSAVE.EXE = ""%Windows%\system32\logon.scr""
To restore registry values this malware/grayware modified:
- Open Registry Editor. To do this:
- On Windows 2000, XP, and Server 2003:
Click Start>Run, type REGEDIT in the text box provided, and then press Enter. - On Windows Vista, 7, and Server 2008:
Click the Start button, type REGEDIT in the Search input field then press Enter. - On Windows 8, 8.1, and Server 2012:
Right-click on the lower left corner of the screen and click Run, type REGEDIT in the Run input field, and then press Enter.
- In the left panel, double-click the following:
HKEY_CURRENT_USER>Control Panel>Desktop - In the right panel, locate the registry value:
SCRNSAVE.EXE = "%User Profile%\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}\hostname.exe " - Right-click on the value name and choose Modify. Change the value data of this entry to:
SCRNSAVE.EXE = "%Windows%\system32\logon.scr" - Close Registry Editor.
Step 7
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%\hostname.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%\hostname.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%\hostname.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 8
Search and delete this folder
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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.
- %User Profile%\Application Data\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}
To delete the malware/grayware folder:
- Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
- In the Named input box, type:
- %User Profile%\Application Data\{BBB0A103-FF77-4DC1-F23C-E8E62C405DA0}
- In the Look In drop-down list, select My Computer, then press Enter.
- Once located, select the folder then press SHIFT+DELETE to permanently delete the folder.
Step 9
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom_CERBER.BYX. 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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