The Win32/Rbot family of backdoor Trojans targets certain versions of Microsoft Windows. After the Trojan infects a computer, it allows attackers to control the computer through an IRC channel. Some commands instruct Win32/Rbot to spread to other computers by scanning for network shares with weak passwords, exploiting various Windows vulnerabilities, or spreading through backdoor ports opened by other families of malicious software. The Trojan also allows attackers to perform other backdoor functions, such as launching denial of service (DoS) attacks against certain Web sites and retrieving system information from infected computers. 

Your computer may be infected with a Win32/Rbot variant if you experience one or more of the following symptoms:

Note: August 15, 2005 - A new variant of Backdoor:Win32/Rbot has been discovered that adds the capability of spreading by exploiting Plug-and-Play vulnerability that is fixed in Microsoft Security Bulletin MS05-039.

 

Note: June 7, 2005 - A new variant of Backdoor:Win32/Rbot has been discovered that adds the capability of spreading by exploiting the Windows ASN.1 vulnerability that is fixed in Microsoft Security Bulletin MS04-007.

 

When Win32/Rbot runs, it copies itself to %windir% or <system folder>. In many cases, it adds a value to registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

These changes cause the Trojan to run whenever Windows starts. Some variants can also add a Windows system service to attain similar results.

 

Win32/Rbot can spread to remote computers by trying weak passwords that it draws from a list. The Trojan may also scan for open ports and connect to a specific IRC server and join a specific channel to receive commands, such as IRC commands to exploit various Windows vulnerabilities. For example, it may exploit the MS03-026 vulnerability to create a remote shell on the target computer. The Trojan uses the remote shell to copy itself to the remote computer, and then creates a task to run the copy. The Trojan can also be instructed through IRC commands to spread through backdoor ports opened by Mydoom, Bagle, Optix, Netdevil, and other families of malicious software.

 

Other remote commands may include actions such as:

 

Some variants of Win32/Rbot terminate security-related product processes. Later variants can overwrite the Windows system host file, <system folder>\drivers\etc\hosts, to block access to security-related Web sites. Other variants can install kernel-mode rootkit Virtool/WinNT.FURootkit.A, which hides the Trojan process from Task Manager and other process-viewer applications.

• Enable a firewall on your computer.
• Get the latest computer updates.
• Use up-to-date antivirus software.
• Use caution with attachments and file transfers.

Enable a firewall on your computer

1. Click Start, and click Control Panel.
2. Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
3. Click Change Windows Firewall Settings.
4. Select On.
5. Click OK.

Get the latest computer updates

1. Click Start, and click Control Panel. 
2. Click System.
3. Click Automatic Updates.
4. Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.

Use up-to-date antivirus software

Use caution with attachments and file transfers