Earlier this year, image spam was all the rage. Today, its greeting card spam, file attachments spam and even spam with URLs from Chinese domains.

As spammers continue to unveil new innovations to peddle their wares and grow their spam footprint, small businesses have a number of options for mitigating risk. From dynamic, next-generation appliances, software and services to employee education, small businesses have more ways than ever to reduce their exposure to this evolving threat.

Spam Trends

While the volume of image spam has decreased considerably since the beginning of the year, it has not gone away. Image spam is a spam email that does not use text in the body of the email to convey its message. Instead, it uses an image embedded in the email. This enables the spam to evade blocking techniques that rely on words in the body of a message or that compare the "fingerprint" of a known image spam to an incoming email.

Image spam

The decline of image spam is likely a result of new antispam technologies that detect and block it. Vendors have worked quickly to enhance their rule filters to target different aspects of message bodies and headers as attacks mutate. Better yet, the most advanced security technology providers are leveraging their networks of millions of probe email accounts throughout the world to catch and collect the addresses of spam senders. Together with cutting-edge detection engines, this technology is highly effective at helping stop image-based attacks.

Of course, spammers are not standing still. Indeed, greeting card spam containing links to viruses is on the rise. The content of these messages often includes links ranging from everyday greetings to holiday-specific cards, and spammers use a variety of hooks to entice users into clicking on malicious links. One high-profile example in August attempted to fool users into thinking they were going to watch a video from a highly popular video-sharing website. Typically, when the user clicks on such a link, however, a staged downloader is delivered-that is, a program that accesses the Internet and downloads a Trojan horse onto the suspecting user's computer. Infected machines, in turn, become part of the very botnet that is responsible for sending such messages and hosts the websites that cause the malware to spread.

Spammers also routinely try out the use of various types of attachments to propagate spam, including PDF files as well as Excel and Zip files. As with image spam, vendors are tackling this problem and delivering antispam filters that identify and filter out the offending messages.

Spammers also continue to use different top-level domains (TLDs) to register specific names that represent their particular product or services. Then, as that particular domain name gets blacklisted, they switch to another. At the same time, spam is becoming more localized, with spammers using country TLDs to target a specific market or region. These trends are now converging. While spammed URLs historically have utilized "net" and "com" TLDs, a growing number of spam messages are using the TLD "cn," which indicates China.

Regardless of the delivery technique, spam remains a serious security concern because it can be used to deliver Trojan horses, viruses, and phishing attempts.  The latest Symantec Internet Security Threat Report estimated in the first half of 2007, that one out of every 233 spam emails contained malicious code. The volumes of spam can not only cause a loss of service or degradation in the performance of network resources and email gateways, the delivery of malicious code through spam can significantly impact resources in trying eradicate it from your systems. As a result, dealing with spam has become a priority for virtually all small businesses today.

Controlling Spam

Several technology options are available to help organizations reduce their exposure to spam. When combined with best practices, these approaches can significantly mitigate risk to the organization, even as spammers change tactics and techniques.

Employees should be educated to help deter spam by never responding to suspicious emails or obvious spam messages-not even to request to be taken off a spammer's list. Doing so usually simply verifies to the spammer that he or she has found a legitimate email address. Employees can also reduce their exposure to spam by viewing emails in plain text rather than in HTML format.

In addition, small businesses can leverage any of today's advanced appliances, applications or mail security services to curb spam. The most effective solutions utilize the latest spam data and constantly update their filtering rules to keep pace with the changing nature of spam.

For many small businesses, an appliance represents a low-maintenance solution. A security appliance usually can be easily integrated into an existing business network and will work together with an existing email server or gateway. An appliance is easy to set up and maintain, automatically updates rules and software, and provides extensive reporting and personalization.

Antispam software can be a low-cost, flexible option for organizations, particularly those that have extra hardware on hand. While antispam software solutions also provide reporting and personalization capabilities similar to those offered by appliances, they require a bit more effort to set up and maintain.

To get enterprise-level  spam protection without draining internal IT resources, a growing number of small businesses are opting for an outsourced antispam service. By outsourcing email security to a managed security services provider, small businesses eliminate the overhead and maintenance typically associated with other antispam approaches. And, for companies who lack the IT staff or expertise to adequately deal with email security challenges, an outsourced service represents an effective option for enjoying 24×7 support from security experts who keep a constant eye on the threat landscape and act quickly to protect their client's business.

Spammers will likely continue to come up with new tactics in their ongoing quest to evade antispam filtering technologies and promote their dubious wares. Antispam vendors, in turn, will work to create innovative new remediation tools and services to help businesses protect against this changing threat. By putting in place the hardware, software, or services most appropriate for their organization, small businesses can reduce their vulnerability to spammers and their ever-evolving bag of tricks.

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