BKDR_LAYORK.AB

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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It connects to certain websites to send and receive information.

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 files:

• %Application Data%\Windows Update\logs.ini
• %Application Data%\Windows Update\wininit.dll - detected as TROJ_ORSAM.BIX

(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:

• %Application Data%\Windows Update\wininit32.exe
• %Application Data%\sysinfo.dat

(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 creates the following folders:

• %Application Data%\Windows Update
• %Application Data%\Windows Update\logs

(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 is injected into the following processes running in memory:

• explorer.exe

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

Autostart Technique

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

HKEY_CURRENT_USER\Software\Classes\
Software\Microsoft\Windows NT\
CurrentVersion\Windows
load = %Application Data%\Windows Update\wininit32.exe

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
load = %Application Data%\Windows Update\wininit32.exe

(Note: The default value data of the said registry entry is {blank}.)

Dropping Routine

This backdoor sets the attributes of its dropped file(s) to the following:

• Hidden
• System
• Read Only

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This backdoor connects to the following website to send and receive information:

• http://{BLOCKED}bar.dns0755.net/{BLOCKED}supdatev7/search{random}