Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = %Application Data%\Microsoft\Windows\shell.exe
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
svchost = %Application Data%\Microsoft\svchost.exe
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = %User Temp%\dwm.exe
(Note: The default value data of the said registry entry is {blank}.)
Other System Modifications
This backdoor adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = http=127.0.0.1:50370
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = 1
(Note: The default value data of the said registry entry is 0.)
HKEY_CURRENT_CONFIG\Software\Microsoft\
windows\CurrentVersion\Internet Settings
ProxyEnable = 1
(Note: The default value data of the said registry entry is 0.)
Dropping Routine
This backdoor drops the following files:
- %Application Data%\Microsoft\stor.cfg - non-malicious file
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
Download Routine
This backdoor connects to the following malicious URLs:
- http://{BLOCKED}evideochanel.com
- http://{BLOCKED}onitoringservice.com
- http://{BLOCKED}udiodevice.com
- http://{BLOCKED}fectivecasino.com
- http://{BLOCKED}.com
It saves the files it downloads using the following names:
- %User Temp%\dwm.exe
- %Application Data%\Microsoft\svchost.exe
- %Application Data%\Microsoft\Windows\shell.exe
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.
Other Details
This backdoor does the following:
- Downloads an updated copy of itself or other malicious files from the said servers by sending HTTP GET request. It does this by appending any of the following strings:
- /im133.jpg?tq={parameter}
- /im134.jpg?tq={parameter}
- /im135.jpg?tq={parameter}
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
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.
Step 3
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 NT\CurrentVersion\Winlogon
- Shell = %Application Data%\Microsoft\Windows\shell.exe
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- svchost = %Application Data%\Microsoft\svchost.exe
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- ProxyServer = http=127.0.0.1:50370
To delete the registry value this malware created:
- Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.
- In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows NT>CurrentVersion>Winlogon - In the right panel, locate and delete the entry:
Shell = %Application Data%\Microsoft>Windows>shell.exe - In the left panel of the Registry Editor window, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
svchost = %Application Data%\Microsoft>svchost.exe - In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Internet Settings - In the right panel, locate and delete the entry:
ProxyServer = http - Close Registry Editor.
Step 4
Restore this modified 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 NT\CurrentVersion\Windows
- From: load = %User Temp%\dwm.exe
To: {blank}
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- From: ProxyEnable = 1
To: 0
- In HKEY_CURRENT_CONFIG\Software\Microsoft\windows\CurrentVersion\Internet Settings
- From: ProxyEnable = 1
To: 0
To restore the registry value this malware/grayware modified:
- Open Registry Editor. Click Start>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 NT>CurrentVersion>Windows - In the right panel, locate the registry value:
load = %User Temp%\dwm.exe - Right-click on the value name and choose Modify. Change the value data of this entry to:
load = {blank} - In the left panel, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Internet Settings - In the right panel, locate the registry value:
ProxyEnable = 1 - Right-click on the value name and choose Modify. Change the value data of this entry to:
ProxyEnable = 0 - In the left panel, double-click the following:
HKEY_CURRENT_CONFIG>Software>Microsoft>windows>CurrentVersion>Internet Settings - In the right panel, locate the registry value:
ProxyEnable = 1 - Right-click on the value name and choose Modify. Change the value data of this entry to:
ProxyEnable = 0 - Close Registry Editor.
Step 5
Search and delete this file
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There may be some component 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. %Application Data%\Microsoft\stor.cfg
To delete the malware/grayware/spyware file:
- Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
- In the Named input box, type:
%Application Data%\Microsoft\stor.cfg
- 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.
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_CYCBOT.BC. 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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