Alert level

Worm:Win32/Conficker.B!inf


Encyclopedia entry
Updated: Oct 30, 2009  |  Published: Feb 12, 2009

Aliases
Not available

Alert Level (?)
Severe

Antimalware protection details
Microsoft recommends that you download the latest definitions to get protected.
Detection last updated:
Definition: 1.59.773.0
Released: Jun 03, 2009 		Detection initially created:
Definition: 1.49.1706.0
Released: Jan 09, 2009

Summary

Worm:Win32/Conficker.B is a worm that infects other computers across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, it could allow remote code execution when file sharing is enabled. It may also spread via removable drives and weak administrator passwords. It disables several important system services and security products.
 
Microsoft strongly recommends that users apply the update referred to in  Security Bulletin MS08-067 immediately.
 
Microsoft also recommends that users ensure that their network passwords are strong to prevent this worm from spreading via weak administrator passwords. More information is available here.
 
Microsoft also recommends that users apply an update that changes the AutoPlay functionality in Windows to prevent this worm from spreading via USB drives. More information is available in the Microsoft Knowledgebase Article KB971029 .

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Symptoms

System Changes
The following system changes may indicate the presence of this malware:
  • The following services are disabled or fail to run:
    • Windows Update Service
    Background Intelligent Transfer Service
    Windows Defender
    Windows Error Reporting Services
  • Some accounts may be locked out due to the following registry modification, which may flood the network with connections:
    • HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
    "TcpNumConnections" = "0x00FFFFFE"
  • Users may not be able to connect to websites or online services that contain the following strings:
    • virus
    spyware
    malware
    rootkit
    defender
    microsoft
    symantec
    norton
    mcafee
    trendmicro
    sophos
    panda
    etrust
    networkassociates
    computerassociates
    f-secure
    kaspersky
    jotti
    f-prot
    nod32
    eset
    grisoft
    drweb
    centralcommand
    ahnlab
    esafe
    avast
    avira
    quickheal
    comodo
    clamav
    ewido
    fortinet
    gdata
    hacksoft
    hauri
    ikarus
    k7computing
    norman
    pctools
    prevx
    rising
    securecomputing
    sunbelt
    emsisoft
    arcabit
    cpsecure
    spamhaus
    castlecops
    threatexpert
    wilderssecurity
    windowsupdate

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Technical Information (Analysis)

Worm:Win32/Conficker.B is a worm that infects other computers across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, it could allow remote code execution when file sharing is enabled. It may also spread via removable drives and weak administrator passwords. It disables several important system services and security products.
 
Worm:Win32/Conficker.B!inf is the detection used for the autorun.inf files created by Conficker.B when it attempts to spread via mapped and removable drives. For more information, please see the Worm:Win32/Conficker.B description elsewhere in our encyclopedia.

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Prevention

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, including Security Bulletin MS08-067.
  • Use up-to-date antivirus software.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to web pages.
  • Protect yourself against social engineering attacks.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
To turn on the Windows Firewall in Windows Vista
  1. Click Start, and click Control Panel.
  2. Click Security.
  3. Click Turn Windows Firewall on or off.
  4. Select On.
  5. Click OK.
To turn on the Internet Connection Firewall in Windows XP
  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
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 websites.
 
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.
To turn on Automatic Updates in Windows Vista
  1. Click Start, and click Control Panel. 
  2. Click System and Maintainance.
  3. Click Windows Updates.
  4. Select a setting. Microsoft recommends selecting Install updates automatically and choose a time that is convenient for you. 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.
To turn on Automatic Updates in Windows XP
  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 Strong Administrator Passwords
Microsoft also recommends that users ensure that their network passwords are strong to prevent this worm from spreading via weak administrator passwords. More information is available here.
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/protect/computer/viruses/vista.mspx.
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 or are 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. please see our article '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, please see our article 'What is social engineering?'.

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Recovery

Microsoft strongly recommends that users apply the update referred to in  Security Bulletin MS08-067 immediately.
 
Microsoft also recommends that users ensure that their network passwords are strong to prevent this worm from spreading via weak administrator passwords. More information is available here .
 
Microsoft also recommends that users apply an update that changes the AutoPlay functionality in Windows to prevent this worm from spreading via USB drives. More information is available in the Microsoft Knowledgebase Article KB971029 .
 
To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as Microsoft Security Essentials, or the Windows Live OneCare safety scanner. For more information about using antivirus software, see http://www.microsoft.com/security/antivirus/av.aspx.
 
Note: Computers infected by Conficker may be unable to connect to web sites related to security applications and services that may otherwise assist in the removal of this worm (for example, downloading antivirus updates may fail). In this case users will need to use an uninfected computer in order to download any appropriate updates or tools and then transfer these to the infected computer.
 
Microsoft Help and Support have provided a detailed guide to removing a Conficker.B infection from an affected computer, either manually or by using the MSRT (Malicious Software Removal Tool).
 
For detailed instructions on how to manually remove Conficker.B, view the following article using an uninfected computer:
http://support.microsoft.com/kb/962007 - Virus alert for Win32/Conficker.B and manual removal instructions
 
Additional information on deploying MSRT in an enterprise environment can be found here:
http://support.microsoft.com/kb/891716 - Deployment of MSRT in an enterprise environment

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