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 disables Task Manager, Registry Editor, and Folder Options.
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 adds the following processes:
- %System%\cmd.exe /C AT /delete /yes
- %System%\cmd.exe /C AT 09:00 /interactive /EVERY:m,t,w,th,f,s,su %System%\RVHOST.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
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
Yahoo Messengger = "%System%\RVHOST.exe"
Other System Modifications
This Worm adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows NT\CurrentVersion\
Winlogon
Shell = "Explorer.exe RVHOST.exe"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\Schedule
AtTaskMaxHours = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WorkgroupCrawler\Shares
shared = "\New Folder.exe"
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
NofolderOptions = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"
Dropping Routine
This Worm drops the following files:
- %System%\setting.ini
- %Windows%\RVHOST.exe
- %System%\RVHOST.exe
- F:\New Folder.exe
- F:\data\photos\photos.exe
- F:\data\data.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
Other Details
This Worm connects to the following possibly malicious URL:
- http://nhatquanglan2.{BLOCKED}h.com/setting.nql
This report is generated via an automated analysis system.
Step 1
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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 7 and Windows Server 2008 (R2) 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.
• For Windows 10 users
- Press Windows logo key + I on your keyboard to open Settings. If that doesn't work, select the Start button, then select Settings.
- Select Update & Security > Recovery.
- Under Advanced startup, select Restart now.
- After your PC restarts to the Choose an option screen, select Troubleshoot > Advcanced options > Startup settings > Restart.
- After your PC restarts, you'll see a list og options. Select 4 or press F4 to start your PC in Safe Mode.
Step 3
Identify and terminate files detected as Worm.Win32.SOHANAD.CU
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- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
To terminate the malware/grayware/spyware process:
- Scan your computer with your Trend Micro product and take note of the name of the malware/grayware/spyware detected.
- Open Windows Task Manager. To do this, press CTRL+SHIFT+ESC.
- View the list of all running programs. To do this:
• For Windows 7 and Server 2008 (R2) users, click the Processes tab.
• For Windows 8, 8.1, 10, and Server 2012 (R2) users, click the Details tab. - In the list of running programs, locate a malware/grayware/spyware file detected earlier.
- Select the detected files, then press either the End Task or the End Process button, depending on the version of Windows you are using.
- Do the same for the remaining detected malware/grayware/spyware files in the list of running programs.
- To check if the malware/grayware/spyware process has been terminated, close Task Manager, and then open it again.
- Close Task Manager.
Step 4
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 7 and Server 2008 (R2) users:
Click start. Type Notepad, then press Enter. - For Windows 8, 8.1, 10, and Server 2012 (R2) 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.
Screen reader support enabled.
To enable Registry Editor, Task Manager, and Folder options:
- Open Notepad. To do this:
- For Windows 7 and Server 2008 (R2) users:
Click start. Type Notepad, then press Enter. - For Windows 8, 8.1, 10, and Server 2012 (R2) 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 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
- Yahoo Messengger = "%System%\RVHOST.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Winlogon
- Shell = "Explorer.exe RVHOST.exe"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Schedule
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares
- shared = "\New Folder.exe"
To delete the registry value this malware/grayware created:
- Open Registry Editor.
» For Windows 7 and Windows Server 2008 (R2) users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, Windows 10, and Windows Server 2012 (R2) 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:
Yahoo Messengger = "%System%\RVHOST.exe" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Wow6432Node>Microsoft>Windows NT>CurrentVersion>Winlogon - In the right panel, locate and delete the entry:
Shell = "Explorer.exe RVHOST.exe" - In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>services>Schedule - In the right panel, locate and delete the entry:
AtTaskMaxHours = "0" - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>WorkgroupCrawler>Shares - In the right panel, locate and delete the entry:
shared = "\New Folder.exe" - Close Registry Editor.
Step 6
Search and delete these components
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There may be some components 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.
- %System%\setting.ini
- %Windows%\RVHOST.exe
- %System%\RVHOST.exe
- F:\New Folder.exe
- F:\data\photos\photos.exe
- F:\data\data.exe
To manually delete a malware/grayware file from an affected system:
•For Windows 7, Windows Server 2008 (R2), Windows 8, Windows 8.1, Windows 10, and Windows Server 2012 (R2):
- Open a Windows Explorer window.
- For Windows 7 and Server 2008 (R2) users, click Start>Computer.
- For Windows 8, 8.1, 10, and Server 2012 (R2) users, right-click on the lower-left corner of the screen,then click File Explorer.
- In the Search Computer/This PC input box, type:
- %System%\setting.ini
- %Windows%\RVHOST.exe
- %System%\RVHOST.exe
- F:\New Folder.exe
- F:\data\photos\photos.exe
- F:\data\data.exe
- 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 and Windows Server 2008 (R2).
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.SOHANAD.CU. 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.
