BKDR_AZBREG.AR

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 registry entries related to antivirus programs. Doing this allows this malware to execute its routines without being detected by installed antivirus programs.

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 adds the following folders:

• %Application Data%\{random folder name}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It drops the following copies of itself into the affected system:

• %User Temp%\{random}.exe
• %User Startup%\{random}.exe
• %Application Data%\{random folder name}\{random}.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It adds the following possibly malicious files or file components:

• {All Users' Profile}\Application Data\{random 1}.log
• %Application Data%\{random 2} .log
• %Application Data%\{random 3} .log
• %Application Data%\{random 4}
• %User Temp%\{random}.sys

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Micorsoft Windows Service
ImagePath = %User Temp%\{random}.sys

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random} = "%Application Data\{random folder name}\{random}.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
Userinit = "%System%\userinit.exe,,%Application Data\{random folder name}\{random}.exe"

(Note: The default value data of the said registry entry is "%System%\userinit.exe," .)

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Micorsoft Windows Service

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_MICORSOFT_WINDOWS_SERVICE

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UacDisableNotify = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = "1"

(Note: The default value data of the said registry entry is "0".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = "4"

(Note: The default value data of the said registry entry is "2".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = "4"

(Note: The default value data of the said registry entry is "2".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = "0"

(Note: The default value data of the said registry entry is "1".)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DisableNotifications = "1"

(Note: The default value data of the said registry entry is "0".)

It deletes the following registry entries related to antivirus and security applications:

HKEY_LOCAL_MACHINE\Microsoft\Windows\
CurrentVersion\Run
Windows Defender = "{windows defender path}"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\Microsoft\Windows\
CurrentVersion\Run
Windows Defender =

Other Details

This backdoor connects to the following URL(s) to check for an Internet connection:

• http://google.com
• http://bing.com
• http://yahoo.com

It connects to the following possibly malicious URL:

• {BLOCKED}lrou.com
• {BLOCKED}xefolgkokdqy.com
• {BLOCKED}vwvgqlretxd.com
• {BLOCKED}urhtchwlhwklf.com
• {BLOCKED}yxjibyd.com
• {BLOCKED}kbwhfdiufhaj.com
• {BLOCKED}vxvrq.com
• {BLOCKED}x.com
• {BLOCKED}kvn.com
• {BLOCKED}yyooh.com
• {BLOCKED}cwgaafbtqkt.com
• {BLOCKED}olov.com
• {BLOCKED}ngy.com
• {BLOCKED}vmhsxtk.com
• {BLOCKED}slhqyy.com
• {BLOCKED}dbdkd.com2
• {BLOCKED}xorlyen.com
• {BLOCKED}yutodtr.com