BKDR_POISON.SM4
Backdoor:Win32/Poison.BG (Microsoft); Generic BackDoor!1lx (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Inject.cptb (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.5028360 (FSecure)
Windows 2000, Windows XP, Windows 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 drops the following copies of itself into the affected system:
- %User Profile%\cookies\google.log
(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_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
IgfxTray = "atkctrs32.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
StubPath = "atkctrs32.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
ComponentID = "JAVAVM"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
Version = "5,1,3802,0"
Other System Modifications
This backdoor deletes the following files:
- %System%\21649.tmp
- %System%\dllcache\aio7ux.sys
- %Windows%\Installer\bse75x.msi
- %System%\atkctrs32.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Windows% is the Windows folder, which is usually C:\Windows.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\IpFilterDriver
imagepath = "system32\21649.tmp"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\IpFilterDriver
imagepath = "System32\DRIVERS\ipfltdrv.sys"
(Note: The default value data of the said registry entry is {random values}.)
It deletes the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
Dropping Routine
This backdoor drops the following files:
- %User Profile%\21649.tmp
- %System%\win.ini
- %System%\dllcache\aio7ux.sys
- %Windows%\Installer\bse75x.msi
- %System%\atkctrs32.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.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %Windows% is the Windows folder, which is usually C:\Windows.)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{BLOCKED}.13.5:80/search?{random characters}
- http://management.{BLOCKED}s.net:80/search?{random characters}
- http://{BLOCKED}.13.5:80/s?{random characters}
- http://{BLOCKED}.13.5:80/aq?{random characters}
- http://{BLOCKED}.13.5:80/aqi?{random characters}
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\Windows\CurrentVersion
- RunOnce
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
- {A9C18355-E2E5-B33E-97E3-8C874D1BB624}
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\RunOnce
- IgfxTray = "atkctrs32.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
- StubPath = "atkctrs32.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
- ComponentID = "JAVAVM"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A9C18355-E2E5-B33E-97E3-8C874D1BB624}
- Version = "5,1,3802,0"
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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\IpFilterDriver
- From: imagepath = "system32\21649.tmp"
To: imagepath = ""{random values}""
- From: imagepath = "system32\21649.tmp"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\IpFilterDriver
- From: imagepath = "System32\DRIVERS\ipfltdrv.sys"
To: imagepath = ""{random values}""
- From: imagepath = "System32\DRIVERS\ipfltdrv.sys"
Step 6
Search and delete these components
- %User Profile%\21649.tmp
- %System%\win.ini
- %System%\dllcache\aio7ux.sys
- %Windows%\Installer\bse75x.msi
- %System%\atkctrs32.exe
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_POISON.SM4. 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 8
Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.
- %System%\21649.tmp
- %System%\dllcache\aio7ux.sys
- %Windows%\Installer\bse75x.msi
- %System%\atkctrs32.exe
Step 9
Restore these deleted registry keys/values from backup
*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.
- In HKEY_CURRENT_USER\Software\Microsoft\Active Setup\Installed Components
- {A9C18355-E2E5-B33E-97E3-8C874D1BB624}
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