IM security best practices for SMBs

More on IM Unified messaging comes of age for SMBs IM and blogs next target for litigation

But that external connectivity, if not configured securely, can come with a heavy price. IM allows viruses, Trojans and other malware to piggyback into your networks far easier than email attachments. IM messages can contain links to malicious Web sites, and confidential data can be compromised. Spam over IM (SPIM) is also a threat.

Thus, security for IM is essential. Here are some suggestions and best practices for securing IM without breaking the bank:

• Designate one IM tool. For internal IM, make sure to use a single enterprise software application. More vendors are offering IM products for SMBs, such as IBM's Lotus Sametime. It installs on its own dedicated server, which is tucked deep inside your company's firewall. Harden that server as you would any other: limit access to authorized users, turn off unnecessary services, install antivirus software and keep patches up to date. Install the client piece of the product only on desktops that have been equally hardened with up-to-date antiviral protection and host-based firewalls.
• Restrict external IM usage. Allow usage only for employees who have to communicate real time. Don't use consumer IM products from America Online, Yahoo Inc. or Microsoft. Use enterprise instant messaging (EIM) software such as Jabber or Akonix.
• Make sure your EIM provider offers some kind of encryption. You can always encrypt with Secure Sockets Layer at no extra cost. Remember, IM messages are conventional HTTP traffic, whether the messages go over port 80 or not.
• Restrict access. Like your internal IM servers, those hosting your EIM should be locked down with restricted access, hardening and updated patches and antiviral protection. They should be hidden behind your company's firewalls, but unlike your internal IM servers, they will need access to the Internet. Make sure to add rules to your firewall allowing access only to your EIM and blocking common ports for consumer IM products.
• Restrict communication. Configure buddy lists on your EIM to restrict communication to only known and trusted parties. This will prevent a malicious user from trying to access your network via IM.
• Log and monitor all IM traffic. This can be used to detect malicious inbound traffic, or inappropriate outbound traffic, like someone trying to send out confidential company data or files.

Joel Dubin, CISSP, is an independent computer security consultant. He is a Microsoft MVP specializing in Web and application security, and is the author of The Little Black Book of Computer Security, available from Amazon.com. He also runs The IT Security Guy blog at http://www.theitsecurityguy.com.

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