W32.Enviar.A

SUMMARY

This is a Visual Basic worm that attempts to use Winsock OCX calls to send itself as email directly to an SMTP mail server.

Protection

• Virus Definitions (Intelligent Updater) October 31, 2001

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: Medium
• Subject of Email: (One of many)
• Size of Attachment: 51,712 bytes

TECHNICAL DETAILS

This worm searches files that are in the C:WindowsFavoritos folder for email address to send itself to. It then creates email with one of the following (Portuguese) subjects :

Suas Compras
Submarino - Confirmacao de Pedido
Americanas - Troca de Pedidos
Oi Gatinha !!!
Relatorio de Despesas
Curriculum Vitae
Detetive Gustavo
DVDs/CDs
Saudades de Voce
Dicas de Seguran
Fa Clube Zeze di Camargo & Luciano
Musicas Cifradas
Entrevista - Ultima Chamada
Sugestoes de Canais
Directv - Promocao Especial
Vestibulares - Manuais e Cabaritos
Jogo do Milhao
Provedor America Online
Compra de Revistas
Turismo & Cia
Alo Galera...Onde estao ?

with a sender from one of these addresses:

uol.com.br
bol.com.br
zipmail.com.br
ieg.com.br

and attaches itself to the email.

It then sends the mail using the Worldcomputers.com SMTP server.

It also adds the value:

Network1   NETX1.EXE

to the registry key

HKEY_LOCAL_MACHINEMicrosoftWindowsCurrentVersionRun

so that it runs each time that you start windows.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

To remove this worm, delete files detected as W32.Enviar.A and remove the value that it added to the registry.

To remove the worm:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Delete all files that are detected as W32.Enviar.A.

To edit the registry:

CAUTION: We strongly recommend that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to back up the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the following key:
   
   HKEY_LOCAL_MACHINEMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   Network1   NETX1.EXE
   
5. Click Registry, and then click Exit.