BKDR_PRORAT.SM

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.

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%\services.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.)

It drops the following files:

• %System%\reginv.dll
• %System%\winkey.dll

(Note: %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 adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
DirectX For Microsoft® Windows = "%System%\fservice.exe"

It 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 deletes the following files:

• %System%\Restore\MachineGuid.txt

(Note: %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.)

It adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Bulas = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
FW_KILL = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
XP_FW_Disable = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
XP_SYS_Recovery = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
ICQ_UIN = "084/41/051/069"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Kurban_Ismi = "whbuhl"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Mail = "`cs`i`ljdsoAinul`hm/ed"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Online_List = ""

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Port = "4001"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Sifre = "032547"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Hata = "Invalid memory block address"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
KSil = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5Y99AE78-58TT-11dW-BE53-Y67078979Y}
StubPath = "%Windows%\system\sservice.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
ICQ_UIN2 = ""

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
LanNotifie = ""

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
Tport = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings
ServerVersionInt = "19"

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\
Windows NT Script Host

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT Script Host\Microsoft DxDiag\WinSettings

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{5Y99AE78-58TT-11dW-BE53-Y67078979Y}

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.