BKDR_VAWTRAK.AM
HEUR:Trojan.Win32.Generic (Kaspersky); Backdoor.Win32.Vawtrak.ab (v) (Sunbelt); Trojan horse PSW.Generic11.CBJQ (AVG)
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 itself after execution.
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 file name} = "regsvr32.exe /s "%All Users Profile%\Application Data\{random file name}.dat""
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random file name} = "regsvr32.exe /s "%Program Data%\{random file name}.dat"" - for Windows Vista and Windows 7
Other System Modifications
This backdoor adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 1}
HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 2}
It adds the following registry entries:
HKEY_LOCAL_MACHINE\Policies\Microsoft\
Windows\Safer\CodeIdentifiers
DefaultLevel = "262144"
HKEY_LOCAL_MACHINE\Policies\Microsoft\
Windows\Safer\CodeIdentifiers
TransparentEnabled = "1"
HKEY_LOCAL_MACHINE\Policies\Microsoft\
Windows\Safer\CodeIdentifiers
PolicyScope = "0"
HKEY_CURRENT_USER\SOFTWARE\AppDataLow\
{random key 2}
{random} = "{random}"
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"
Dropping Routine
This backdoor drops the following files:
- %All Users Profile%\Application Data\{random file name}.dat
- %Program Data%\{random file name}.dat - for Windows Vista and Windows 7
(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{BLOCKED}.{BLOCKED}.188.50
- http://{BLOCKED}.{BLOCKED}.56.247
- http://{BLOCKED}n.com.tw
- http://{BLOCKED}g.com.tw
It deletes itself after execution.
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\AppDataLow
- {random key 1}
- {random key 1}
- In HKEY_CURRENT_USER\SOFTWARE\AppDataLow
- {random key 2}
- {random key 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_LOCAL_MACHINE\Policies\Microsoft\Windows\Safer\CodeIdentifiers
- DefaultLevel = "262144"
- DefaultLevel = "262144"
- In HKEY_LOCAL_MACHINE\Policies\Microsoft\Windows\Safer\CodeIdentifiers
- TransparentEnabled = "1"
- TransparentEnabled = "1"
- In HKEY_LOCAL_MACHINE\Policies\Microsoft\Windows\Safer\CodeIdentifiers
- PolicyScope = "0"
- PolicyScope = "0"
- 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\AppDataLow\{random key 2}
- {random} = "{random}"
- {random} = "{random}"
- In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Run
- {random file name} = "regsvr32.exe /s "%All Users Profile%\Application Data\{random file name}.dat""
- {random file name} = "regsvr32.exe /s "%All Users Profile%\Application Data\{random file name}.dat""
- In HKEY_CURRENT_USER\Microsoft\Windows\CurrentVersion\Run
- "regsvr32.exe /s "%Program Data%\{random file name}.dat"" - for Windows Vista and Windows 7
- "regsvr32.exe /s "%Program Data%\{random file name}.dat"" - for Windows Vista and Windows 7
Step 5
Search and delete this file
- %All Users Profile%\Application Data\{random file name}.dat
- %Program Data%\{random file name}.dat
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_VAWTRAK.AM. 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.
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_VAWTRAK.AM. 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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