W32.Chir@mm
Risk Level 2: Low
Discovered: June 8, 2002
Updated: February 13, 2007 11:54:44 AM
Also Known As: W32.Chier@mm
Type: Worm
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
SUMMARY
W32.Chir@mm is a mass-mailing worm. It uses its own SMTP engine to send itself to email addresses. The SMTP server that the worm uses is a static one, which means that if a specific SMTP server is not running, the worm cannot spread.
The worm creates Runouce.exe (note the letter "u") in the %System% folder. Runouce.exe has the same form as the worm file that was originally received as an email attachment. The email message arrives with the following characteristics:
From:
Subject: Hi, i am
Attachments: P.exe
W32.Chir@mm also searches across the network and accesses files on other computers. However, due to a bug, these files are not modified in any way.
If you open the message in an unpatched version of Microsoft Outlook or Outlook Express, the attachment may be executed automatically. Information about this vulnerability and a patch are available at:
http://www.microsoft.com/technet/security/bulletin/MS01-020.asp
NOTE: Definitions dated prior to June 11, 2002 will detect this as W32.Chier@mm.
Antivirus Protection Dates
- Initial Rapid Release version June 8, 2002
- Latest Rapid Release version July 19, 2008 revision 019
- Initial Daily Certified version June 8, 2002
- Latest Daily Certified version January 20, 2009 revision 048
- Initial Weekly Certified release date June 8, 2002
Threat Assessment
Wild
- Wild Level: Low
- Number of Infections: 0 - 49
- Number of Sites: 0 - 2
- Geographical Distribution: Low
- Threat Containment: Easy
- Removal: Easy
Damage
- Damage Level: Low
Distribution
- Distribution Level: High
TECHNICAL DETAILS
This worm uses both an IFRAME exploit and a MIME exploit to execute the worm on your system. Because of this, it is possible that the worm could be executed simply by previewing the email in your email program.
When it is executed, the file \%System%\Runouce.exe is created; the file's attributes are set to Hidden, System, and Read-Only. These attributes prevent you from seeing the file in Windows Explorer if Windows Explorer is configured with its default settings.
NOTE: %System% is a variable. The worm locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.
W32.Chir@mm also adds the STRING value:
Runonce C:\Windows\System\Runouce.exe
to the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
The worm sends email to all contacts found in the Windows Address Book. The email has the following characteristics:
From:
Subject: Hi, i am
Attachments: P.exe
W32.Chir@mm also searches across the network and accesses files on other computers. However, due to a bug, these files are not modified in any way.
Recommendations
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":- Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
- Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
- Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
- Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
- Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
- Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
- If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
- Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
- Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
- Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
- Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
- If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
- For further information on the terms used in this document, please refer to the Security Response glossary.
REMOVAL
To remove this worm:
- Update the virus definitions, restart in Safe mode, and run a full system scan. Delete all files that are detected as W32.Chir@mm.
- Delete the value
Runonce \Windows\System\Runouce.exe
from the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
W32.Chir@mm
Risk Level 2: Low
Discovered: June 8, 2002
Updated: February 13, 2007 11:54:44 AM
Also Known As: W32.Chier@mm
Type: Worm
Systems Affected: Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows XP
SUMMARY
W32.Chir@mm is a mass-mailing worm. It uses its own SMTP engine to send itself to email addresses. The SMTP server that the worm uses is a static one, which means that if a specific SMTP server is not running, the worm cannot spread.
The worm creates Runouce.exe (note the letter "u") in the %System% folder. Runouce.exe has the same form as the worm file that was originally received as an email attachment. The email message arrives with the following characteristics:
From:
Subject: Hi, i am
Attachments: P.exe
W32.Chir@mm also searches across the network and accesses files on other computers. However, due to a bug, these files are not modified in any way.
If you open the message in an unpatched version of Microsoft Outlook or Outlook Express, the attachment may be executed automatically. Information about this vulnerability and a patch are available at:
http://www.microsoft.com/technet/security/bulletin/MS01-020.asp
NOTE: Definitions dated prior to June 11, 2002 will detect this as W32.Chier@mm.
Antivirus Protection Dates
- Initial Rapid Release version June 8, 2002
- Latest Rapid Release version July 19, 2008 revision 019
- Initial Daily Certified version June 8, 2002
- Latest Daily Certified version January 20, 2009 revision 048
- Initial Weekly Certified release date June 8, 2002
Threat Assessment
Wild
- Wild Level: Low
- Number of Infections: 0 - 49
- Number of Sites: 0 - 2
- Geographical Distribution: Low
- Threat Containment: Easy
- Removal: Easy
Damage
- Damage Level: Low
Distribution
- Distribution Level: High
TECHNICAL DETAILS
This worm uses both an IFRAME exploit and a MIME exploit to execute the worm on your system. Because of this, it is possible that the worm could be executed simply by previewing the email in your email program.
When it is executed, the file \%System%\Runouce.exe is created; the file's attributes are set to Hidden, System, and Read-Only. These attributes prevent you from seeing the file in Windows Explorer if Windows Explorer is configured with its default settings.
NOTE: %System% is a variable. The worm locates the \Windows\System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.
W32.Chir@mm also adds the STRING value:
Runonce C:\Windows\System\Runouce.exe
to the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
The worm sends email to all contacts found in the Windows Address Book. The email has the following characteristics:
From:
Subject: Hi, i am
Attachments: P.exe
W32.Chir@mm also searches across the network and accesses files on other computers. However, due to a bug, these files are not modified in any way.
Recommendations
- Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
- Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
- Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
- Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
- Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
- Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
- If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
- Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
- Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
- Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
- Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
- If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
REMOVAL
To remove this worm:
- Update the virus definitions, restart in Safe mode, and run a full system scan. Delete all files that are detected as W32.Chir@mm.
- Delete the value
Runonce \Windows\System\Runouce.exe
from the registry key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
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