May 03, 2011
Nov 08, 2005
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Win32/IRCbot is a large family of backdoor Trojans that targets computers running Microsoft Windows. The Trojan drops other malicious software and opens a backdoor on the infected computer to connect to IRC servers. The Trojan can maintain multiple IRC server connections simultaneously to receive commands from attackers.
There are no readily apparent indications of infection by Win32/IRCbot. The name of the Trojan file copy and corresponding registry settings may differ according to the particular variant of Win32/IRCbot.
Technical Information (Analysis)
Win32/IRCbot takes the following actions:
Creates a copy of itself on the infected computer. The location and name of the dropped file varies. The Trojan also adds a value and data to an autostart registry key such as HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
so that the Trojan runs automatically each time Windows starts. For example, one particular variant of Win32/IRCbot creates a copy of itself at %windir%\mwoffice.exe and adds value "Windows Update Controller" with data "%windir%\mwoffice.exe" to this autostart registry key.
Drops other malicious software, such as variants of:
Opens a backdoor in order to connect to certain IRC servers. The Trojan then joins specified IRC channels to receive attacker commands to perform operations such as the following:
Download and run other malicious software
Release information, such as system information and directory and file listings
Conduct denial of service attacks
Take the following steps to help prevent infection on your system:
Enable a firewall on your computer.
Get the latest computer updates for all your installed software.
Use up-to-date antivirus software.
Use caution when opening attachments and accepting file transfers.
Use caution when clicking on links to Web pages.
Avoid downloading pirated software.
Protect yourself against social engineering attacks.
Use strong passwords.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor Web sites.
You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
Use up-to-date antivirus software
Use caution when opening attachments and accepting file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.
Use caution when clicking on links to Web pages
Exercise caution with links to Web pages that you receive from unknown sources, especially if the links are to a Web page that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your system simply by visiting a Web page with harmful content.
Avoid downloading pirated software
Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software
Protect yourself from social engineering attacks
While attackers may attempt to exploit vulnerabilities in hardware or software in order to compromise a system, they also attempt to exploit vulnerabilities in human behavior in order to do the same. When an attacker attempts to take advantage of human behavior in order to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted system. For more information, see 'What is social engineering?
Use strong passwords
Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least 8 characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx
To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:
For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.