Backdoor:W32/IRCBot.AAS

This IRCBot connects to an IRC server at dark.bestunix.org, where it waits for commands from a remote user. The bot is controlled via messages sent to it.

Installation

Upon execution, Backdoor.Win32.IRCBot.AAS drops a copy of itself in the Windows System directory as:

• algose32.exe

This program takes advantage of the MS06-040 vulnerability. A specially crafted packet is embedded in the body of the program and is XOR'ed by 99h. The program will then wait for a "Scan" command from a remote user.

On receiving the command, the program sends the packet to all IP addresses that the remote user specifies. The payload of the packet is that it downloads a file from a URL and executes it. The URL the file is downloaded from is:

• http://www.emr3.net/p[...].exe.

The file downloaded is detected as Backdoor.Win32.IRCBot.WT.

Activity

This malware connects to an IRC server and joins the password-protected channel #!e!, using a random nickname. It then waits for commands from a remote user.

To be able to gain access to the backdoor, the remote user must login to the channel and type the password:

When successfully logged in to the BOT, the remote user can do the following IRC commands:

• Joins/Part an IRC channel
• Send private/channel messages
• Change the BOT's nick
• Quits the IRC server.
• Checks the BOT's ID and version.
• Check the up-time of the BOT
• Logout from the BOT.
• Update the BOT.

The remote user can also perform the following system commands:

• Opens/Executes/Downloads files.
• Port scanning.
• Access files through a Shell.
• List/Terminate processes.

Registry

This program creates the following registry key as its auto-start technique:

• HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run Offices Monitorse = "%systemdir%\algose32.exe"
• HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run Offices Monitorse = "%systemdir%\algose32.exe"

Note: %systemdir% is typically "C:\Windows\system32".