Malicious Software Encyclopedia: Win32/Esbot
Published:
January 10, 2006
Worm:Win32/Esbot is a family of network worms that targets Microsoft Windows 2000 computers by exploiting the Windows Plug-and-Play buffer overflow vulnerability that is fixed with Microsoft Security Bulletin MS05-039. The worm can also infect computers running other Windows operating systems if it is delivered through e-mail, instant messaging, or other routes. The worm has a backdoor component that connects to an IRC server to receive commands from attackers.
On This Page
Threat Overview
| Class/type | Worm - Network
Trojan - Backdoor
|
| Discovered | August 15, 2005 |
| Circulating | Yes |
| Affected operating systems | Windows 2000
|
| 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):
CA:
Win32.EsbotF-secure:
W32/Backdoor.EURMcAfee:
W32/IRCbot.genSophos:
EsbotSymantec:
EsbotTrend Micro:
BKDR_RBOT
Learn more about the
Microsoft Virus Information Alliance.
Related Security Bulletins
The following Microsoft Security bulletins are related to this issue:
MS05-039 - Vulnerability in Plug and Play Could Allow Remote Code Execution and Elevation of Privilege (899588)Technical Analysis
Win32/Esbot takes the following actions:
Starts the worm service, if possible. If the service starts, the original worm process exits after starting a new explorer.exe process to delete the original worm file. In this case, the service performs the operations that follow. If the service does not start, the original worm process performs the operations.
Checks for the presence of a particular mutex. If the mutex exists, the service or original worm process exits so that multiple instances of the worm are not running concurrently on the same computer. If the mutex does not exist, the service or original worm process takes the following actions:
Creates a mutex to prevent multiple instances of the worm from running on the same computer.
Places data in the EnableDCOM value of registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\OLE
Places data in the restrictanonymous value of registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
- Injects its code into the explorer.exe process space and runs the injected code.
- Scans random IP addresses to exploit the Windows Plug-and-Play vulnerability described in Microsoft Security Bulletin MS05-039. The worm may begin scanning with a random address or an address based on the IP address of the infected computer; it then scans IP addresses consecutively.
Connects to a specific IRC server and channel to enable attackers to perform functions such as the following:
How to Prevent Infection
Follow these 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.
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, and click Network Connections. If you do not see Network and Internet Connections, click Switch to Category View.
Highlight a connection that you want to help protect, and click Change settings of this connection.
Click Advanced, and select Protect my computer and network by limiting or preventing access to this computer from the Internet.
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 Microsoft 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 Performance and Maintenance. If you do not see Performance and Maintenance, click Switch to Category View.
Click System.
Click Automatic Updates, and select Keep my computer up to date.
Select a setting. Microsoft recommends selecting Automatically download the updates, and install them on the schedule that I specify and setting a regular update time.
If you choose to have Automatic Updates notify you in step 5, you will see a notification balloon when new downloads are available to install. Click the notification balloon to review and install updates.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. You should always run antivirus software on your computer that is updated with the latest signature files to automatically help protect you from infection. If you don't have antivirus software installed, you can get it from one of several companies. For more information, see http://www.microsoft.com/athome/security/downloads/default.mspx
How to Tell If Your Computer Is Infected
Win32/Esbot symptoms differ according to the variant. There may be no readily apparent indications that your computer is infected.
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 | Exploits the Windows Plug-and-Play vulnerability (MS05-039). |
Payload Information
| Payload type | Trigger | Description |
|---|
| Creates files | Execution | Copies itself to <system folder>\mousebm.exe. |
| Compromises Security | Execution | Connects to an IRC server to receive commands from attackers. |
| Release information | Execution | Releases information such as system details and file data. |
Affected Ports
| Protocol | Port number |
|---|
| TCP | 445 |
