GEN:SID 1:793
Message VIRUS OUTBOUND .vbs file attachment
Summary This event is generated when an internal mail server sends an e-mail out of the network that may contain a Visual Basic Script (VBS) attachment.
Impact Malicious code infection.  This event may indicate that an internal host may be infected with some kind of malicious code.
Detailed Information An outbound e-mail message that contains an attachment with a file name ending in ".vbs" may indicate that an internal host has been infected by some kind of malicious code.  A ".vbs" extension typically means that an attachment file is a Visual Basic Script.  A VBS attachment may contain executable code for a worm, virus, or trojan.
Affected Systems Microsoft Windows hosts.
Attack Scenarios Malicious code may be spread by e-mail containing attachments with files ending in ".vbs".
Ease of Attack Simple
Corrective Action Make sure that the suspected infected host has the most current anti-virus software.

Run a virus scan on the suspected infected host.

Configure your mail server to block attachments that contain executable code, such as those with extensions of ".vbs", ".exe", etc.
Additional References