BKDR_LIKSEPUT.B

This Trojan 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 commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

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

Arrival Details

This Trojan 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 Trojan drops the following files:

• %User Temp%\reader_sl.exe - also detected as BKDR_LIKSEPUT.B
• %User Temp%\untitled.bmp - non-malicious file

(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.)

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

• %User Profile%\Application Data\Help\svchost.exe

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

It creates the following folders:

• %User Profile%\Application Data\Help

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
testhost = %User Profile%\Application Data\Help\svchost.exe

Backdoor Routine

This Trojan executes the following commands from a remote malicious user:

• create files
• download and execute files
• execute cmd.exe
• execute commands via command-line
• get domain information
• get drive information
• kill processes/services
• list processes/services
• start processes/services

It connects to the following websites to send and receive information:

• 216.213.199.194

Dropping Routine

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

Other Details

This Trojan connects to the following possibly malicious URL:

• http://{BLOCKED}y.{BLOCKED}linesite.com/index.html

NOTES:

It opens the non-malicious image file that it drops using default image viewer to hide its execution.

It parses the content from the abovementioned URL.