Malicious Mobile Code

Email Programs

There are dozens of great email programs on the market today, including Microsoft's Outlook™, Microsoft Outlook Express™ and MSN Hotmail ™, Netscape Messenger ™, Qualcomm's Eudora ™, Lotus Notes™, Lotus cc:Mail ™, Pegasus Mail ™, and Sun Microsystems's Start Office ™. Most email attacks are written specifically for Microsoft Outlook, but can be successful to varying degrees on most of the popular email clients depending on the email program type and exploit.

Types of Email

Email software comes in three basic types:

• Client/server

• Web-based

• Host-based

The most popular type of email today is based on the client/server model. The main email software is located on the local client PC. It contacts a main mail server database to deliver and pick up messages. The mail server collects all messages and distributes them to either email clients or other email servers for further routing to their intended destination (called the store-and-forward model ). Most conventional email systems use the client/server model. Microsoft Exchange, Microsoft Outlook, Netscape Messenger, and Lotus Notes are all client/server email models.

Web-based email systems, such as HotMail or Yahoo! Mail™ , allow end users to pick up their email from any computer with an Internet-connected browser. The user must login with her email name and password. Then she can send and retrieve emails like she normally would, albeit, with less overall functionality. Web-based email creation takes place within ...