BKDR_CYCBOT.SMC
Backdoor:Win32/Cycbot.B (Microsoft); BackDoor-EXI (McAfee); Backdoor.Cycbot!gen1 (Symantec); Trojan-Spy.Win32.Zbot.ates (Kaspersky); Trojan.Win32.Kryptik.agfl (v) (Sunbelt); Gen:Variant.Katusha.3 (FSecure)
Windows 2000, XP, Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
Arrival Details
This backdoor 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 backdoor creates the following folders:
- %User Profile%\Application Data
- %User Profile%\Application Data\Microsoft
- %User Profile%\Microsoft\Windows
- %User Profile%\CryptnetUrlCache\MetaData
- %User Profile%\Microsoft\CryptnetUrlCache
- %User Profile%\CryptnetUrlCache\Content
(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 backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
conhost = "%User Profile%\Microsoft\csrss.exe"
Other System Modifications
This backdoor deletes the following files:
- %User Profile%\Microsoft\stor.cfg
- %User Profile%\Microsoft\svchost.exe
- %User Temp%\dwm.exe
- %User Profile%\Windows\shell.exe
- %Temp%\e9b4.mst
- {malware path and file name}
- %User Profile%\Microsoft\gb_54890.bat
- %User Profile%\Windows\shellu.exe
- %User Profile%\Microsoft\gb_67843.bat
(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.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)
It deletes the following folders:
- %User Profile%\My Pictures\
- %Start Menu%\Programs\Administrative Tools\
(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.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista and 7.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher
HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\Certificates
HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CRLs
HKEY_CURRENT_USER\Software\Microsoft\
SystemCertificates\TrustedPublisher\CTLs
HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher
HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
Certificates
HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CRLs
HKEY_CURRENT_USER\Software\Policies\
Microsoft\SystemCertificates\TrustedPublisher\
CTLs
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe,%User Profile%\Windows\shell.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "explorer.exe,%User Profile%\Application Data\conhost.exe"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Load = "%System%\lvvm.exe"
Dropping Routine
This backdoor drops the following files:
- %User Profile%\Windows\shell.exe
- %User Profile%\Microsoft\svchost.exe
- %User Temp%\dwm.exe
- %User Profile%\Microsoft\gb_54890.bat
- %User Profile%\Microsoft\csrss.exe
- %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
- %User Profile%\Content\2BF68F4714092295550497DD56F57004
- %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
- %User Profile%\Content\94308059B57B3142E455B38A6EB92015
- %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
- %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
- %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
- %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
- %Temp%\e9b4.mst
- %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
- %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
- %System%\lvvm.exe
- %User Profile%\Microsoft\gb_67843.bat
- %User Profile%\Application Data\conhost.exe
- %User Profile%\Windows\shellu.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.. %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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
This report is generated via an automated analysis system.
SOLUTION
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
Step 3
Delete this registry key
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\SystemCertificates
- TrustedPublisher
- In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
- Certificates
- In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
- CRLs
- In HKEY_CURRENT_USER\Software\Microsoft\SystemCertificates\TrustedPublisher
- CTLs
- In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates
- TrustedPublisher
- In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
- Certificates
- In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
- CRLs
- In HKEY_CURRENT_USER\Software\Policies\Microsoft\SystemCertificates\TrustedPublisher
- CTLs
Step 4
Delete this registry value
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- conhost="%User Profile%\Microsoft\csrss.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
- Shell="explorer.exe,%User Profile%\Windows\shell.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
- Shell="explorer.exe,%User Profile%\Application Data\conhost.exe"
Step 5
Restore these modified registry values
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\Software\Microsoft\Windows NT\CurrentVersion\Windows
- Load="%System%\lvvm.exe"
Step 6
Search and delete these folders
- %User Profile%\Application Data
- %User Profile%\Application Data\Microsoft
- %User Profile%\Microsoft\Windows
- %User Profile%\CryptnetUrlCache\MetaData
- %User Profile%\Microsoft\CryptnetUrlCache
- %User Profile%\CryptnetUrlCache\Content
Step 7
Search and delete these components
- %User Profile%\Windows\shell.exe
- %User Profile%\Microsoft\svchost.exe
- %User Temp%\dwm.exe
- %User Profile%\Microsoft\gb_54890.bat
- %User Profile%\Microsoft\csrss.exe
- %User Profile%\MetaData\2BF68F4714092295550497DD56F57004
- %User Profile%\Content\2BF68F4714092295550497DD56F57004
- %User Profile%\MetaData\94308059B57B3142E455B38A6EB92015
- %User Profile%\Content\94308059B57B3142E455B38A6EB92015
- %User Profile%\MetaData\60E31627FDA0A46932B0E5948949F2A5
- %User Profile%\Content\60E31627FDA0A46932B0E5948949F2A5
- %User Profile%\MetaData\0797C381B2F87EB5A1D5573BD15BA4F4
- %User Profile%\Content\0797C381B2F87EB5A1D5573BD15BA4F4
- %Temp%\e9b4.mst
- %User Profile%\MetaData\7B2238AACCEDC3F1FFE8E7EB5F575EC9
- %User Profile%\Content\7B2238AACCEDC3F1FFE8E7EB5F575EC9
- %System%\lvvm.exe
- %User Profile%\Microsoft\gb_67843.bat
- %User Profile%\Application Data\conhost.exe
- %User Profile%\Windows\shellu.exe
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_CYCBOT.SMC. 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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