BKDR_VAWTRAK.SM3
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
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.
It deletes the initially executed copy of itself.
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.
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = "regsvr32.exe "%All Users Profile%\Application Data\{random filename}.dat""
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CLASSES_ROOT\CLSID\{CLSID 1}
HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 1}
HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
NoProtectedModeBanner = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
TabProcGrowth = "0"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"
HKEY_CLASSES_ROOT\CLSID\{CLSID 1}
#cert = "{hex value}"
HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
{CLSID 3} = "{hex value}"
HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 1}
#cert = "{hex value}"
HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
{CLSID 3} = "{hex value}"
HKEY_CLASSES_ROOT\CLSID\{CLSID 2}
{CLSID 4} = "{hex value}"
HKEY_CURRENT_USER\Software\Classes\
CLSID\{CLSID 2}
{CLSID 4} = "{hex value}"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"
Dropping Routine
This backdoor drops the following files:
- %All Users Profile%\Application Data\{random filename}.dat
(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{BLOCKED}.{BLOCKED}.184.239/posting.php?mode=reply&f=47&t={value}&sid={value}
- http://{BLOCKED}.{BLOCKED}.184.239/viewforum.php?f=47&sid={value}
- http://{BLOCKED}ng.com/posting.php?mode=reply&f=47&t={value}&sid={value}
- http://{BLOCKED}ng.com/viewforum.php?f=47&sid={value}
It deletes the initially executed copy of itself
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_CLASSES_ROOT\CLSID
- {CLSID 1}
- {CLSID 1}
- In HKEY_CLASSES_ROOT\CLSID
- {CLSID 2}
- {CLSID 2}
- In HKEY_CURRENT_USER\Software\Classes\CLSID
- {CLSID 1}
- {CLSID 1}
- In HKEY_CURRENT_USER\Software\Classes\CLSID
- {CLSID 2}
- {CLSID 2}
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {random filename} = "regsvr32.exe "%All Users Profile%\Application Data\{random filename}.dat""
- {random filename} = "regsvr32.exe "%All Users Profile%\Application Data\{random filename}.dat""
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- NoProtectedModeBanner = "1"
- NoProtectedModeBanner = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- TabProcGrowth = "0"
- TabProcGrowth = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
- 2500 = "3"
- 2500 = "3"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
- GlobalUserOffline = "0"
- GlobalUserOffline = "0"
Step 5
Search and delete this file
- %All Users Profile%\Application Data\{random filename}.dat
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_VAWTRAK.SM3. 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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