Malicious Software Encyclopedia: Win32/Rbot
Published:
April 20, 2007
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.
On This Page
Threat Overview
| Class/type | Trojan - Backdoor
|
| Discovered | April 16, 2003 |
| Circulating | Yes |
| Affected operating systems | Windows NT 4.0
Windows 95
Windows 2000
Windows XP
Windows Server 2003
|
| Affected software |
Not specified
|
| Infection rating | Medium |
| Recovery difficulty | Moderate |
| Damage rating | Medium |
| Transmission rating | Low |
Aliases (Also Known As)
Different antivirus vendors may be using different names to refer to this malicious software. Here are some of the names currently in use by antivirus software vendors participating in the Microsoft Virus Information Alliance (VIA):
McAfee:
W32/Sdbot.worm.genSymantec:
W32.Spybot.WormTrend Micro:
WORM_RBOT
Learn more about the
Microsoft Virus Information Alliance.
Related Security Bulletins
The following Microsoft Security bulletins are related to this issue:
MS01-059 - Unchecked Buffer in Universal Plug and Play Can Lead to System CompromiseMS02-061 - Elevation of Privilege in SQL Server Web Tasks (Q316333)MS03-001 - Unchecked Buffer in Locator Service Could Lead to Code Execution (810833)MS03-007 - Unchecked Buffer In Windows Component Could Cause Server Compromise (815021)MS03-026 - Buffer Overrun In RPC Interface Could Allow Code Execution (823980)MS03-043 - Buffer Overrun in Messenger Service Could Allow Code Execution (828035)MS03-049 - Buffer Overrun in the Workstation Service Could Allow Code Execution (828749)MS04-007 - ASN .1 Vulnerability Could Allow Code Execution (828028)MS04-011 - Security Update for Microsoft Windows (835732)MS05-039 - Vulnerability in Plug and Play Could Allow Remote Code Execution and Elevation of Privilege (899588)Technical Analysis
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:
Downloading and executing remote files.
Monitoring network traffic.
Launching HTTP/HTTPD, SOCKS4, and TFTP/FTP servers.
Enabling or disabling DCOM protocol.
Retrieving computer configuration information, including Windows logon information, user account information, open shares, file system information, and network connection information.
Logging keystrokes.
Retrieving CD keys of games.
Capturing screens and Webcam shots.
Redirecting TCP traffic.
Uploading files through FTP.
Sending e-mail.
Manipulating processes and services.
Conducting denial of service (DoS) attacks.
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.
How to Prevent Infection
Take the following steps to help prevent infection on your system:
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
Use a third-party firewall product or turn on the Microsoft Windows XP Internet Connection Firewall.
To turn on the Internet Connection Firewall in Windows XP
Click Start, and click Control Panel.
Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
Click Change Windows Firewall Settings.
Select On.
Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. You can use the Automatic Updates feature in Windows XP to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows XP
Click Start, and click Control Panel.
Click System.
Click Automatic Updates.
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
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software that is updated with the latest signature files. Antivirus software is available from several sources. For more information, see http://www.microsoft.com/athome/security/downloads/default.mspx
Use caution with attachments and 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.
How to Tell If Your Computer Is Infected
Your computer may be infected with a Win32/Rbot variant if you experience one or more of the following symptoms:
- The operating system shuts down after displaying a dialog box resembling the following:
- You see an LSA Shell error report dialog box resembling the following:
- Your computer reboots without user interaction. You may see a system shutdown dialog box resembling the following:
How to Recover from Infection
Automatic Recovery
To attempt to automatically remove this threat, run one of the following removal tools:
Transmission Methods
| Method | Description |
|---|
| Exploits Vulnerability | Can exploit various Windows vulnerabilities to spread to a target computers. |
| Network Shares | Can spread to network shares with weak passwords. |
