BKDR_PRORAT.F
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
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 opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.
TECHNICAL DETAILS
875,520 bytes
EXE
Yes
17 Nov 2009
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:
- %Windows%\winlogon.exe
- %Windows%\system\sservice.exe
- %System%\fservice.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
Autostart Technique
This backdoor modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe %System%\fservice.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
Other System Modifications
This backdoor adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Bulas = "1"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
FW_KILL = "1"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
XP_FW_Disable = "1"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
XP_SYS_Recovery = "1"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
ICQ_UIN = ""
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Kurban_Ismi = "bdsdo`jr`o"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Mail = "btsdmhfiu^Ainul`hm/bnl"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Online_List = ""
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Port = "4001"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Sifre = "0370"
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
Hata = ""
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
KSil = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5Y99AE78-58TT-11dW-BE53-Y67078979Y}
StubPath = "%Windows%\system\sservice.exe"
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"
(Note: The default value data of the said registry entry is 0.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sr
Start = "4"
(Note: The default value data of the said registry entry is 0.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sr\Parameters
FirstRun = "1"
(Note: The default value data of the said registry entry is 0.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\srservice
Start = "4"
(Note: The default value data of the said registry entry is 2.)
It adds the following registry keys as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft DirectX
HKEY_CURRENT_USER\Software\Microsoft DirectX\
WinSettings
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5Y99AE78-58TT-11dW-BE53-Y67078979Y}
It creates the following registry entry(ies) to bypass Windows Firewall:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\winlogon.exe = "%Windows%\winlogon.exe:*:Disabled:winlogon"
Backdoor Routine
This backdoor opens a random port to allow a remote user to connect to the affected system. Once a successful connection is established, the remote user executes commands on the affected system.
SOLUTION
9.200
6.630.01
16 Nov 2009
6.631.00
17 Nov 2009
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
Identify and delete files detected as BKDR_PRORAT.F using either the Startup Disk or Recovery Console
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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_CURRENT_USER\Software
- Microsoft DirectX
- Microsoft DirectX
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
- {5Y99AE78-58TT-11dW-BE53-Y67078979Y}
- {5Y99AE78-58TT-11dW-BE53-Y67078979Y}
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\policies\Explorer\Run
- DirectX For Microsoft® Windows = "%System%\fservice.exe"
- DirectX For Microsoft® Windows = "%System%\fservice.exe"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\AuthorizedApplications\List
- %Windows%\winlogon.exe = "%Windows%\winlogon.exe:*:Disabled:winlogon"
- %Windows%\winlogon.exe = "%Windows%\winlogon.exe:*:Disabled:winlogon"
Step 5
Restore this modified 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 NT\CurrentVersion\Winlogon
- From: Shell = "Explorer.exe %System%\fservice.exe"
To: Shell = Explorer.exe
- From: Shell = "Explorer.exe %System%\fservice.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRestore
- From: DisableSR = "1
To: DisableSR = 0
- From: DisableSR = "1
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sr
- From: Start = "4"
To: Start = 0
- From: Start = "4"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sr\Parameters
- From: FirstRun = "1"
To: FirstRun = 0
- From: FirstRun = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\srservice
- From: Start = "4"
To: Start = 2
- From: Start = "4"
Step 6
Scan your computer with your Trend Micro product to delete files detected as BKDR_PRORAT.F. 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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