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Backdoor:W32/IRCBot.AAS

Classification

Category: Malware

Type: Backdoor

Aliases: Backdoor.Win32.IRCBot.AAS

Summary


A remote administration utility which bypasses normal security mechanisms to secretly control a program, computer or network.

Removal


Automatic action

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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Technical Details


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".