Researchers at security software vendor AppRiver said the total amount of spam circulating the Internet in October surged 28 percent from September, but the number of new malware pieces actually declined.

The total number of spam emails in October fluctuated between 80 million and 150 million pieces a day, according to the company's latest Threat and Spamscape report (PDF).

Meanwhile, virus activity tapered off dramatically after spiking early in the month. AppRiver's filters discovered more than 3.5 million infected sites or emails on Oct. 2, likely the fallout from the massive "Here You Have" virus that wreaked havoc on enterprise email servers throughout September and into the early part of last month.


Image spam, either contained within an unsolicited email message or obscured on an infected website, continued to plague Internet users last month, peaking at more than 2.2 million identified instances on Oct. 5 and averaging between 1 million and 1.5 million instance a day for the bulk of the month.

"October was business as usual," AppRiver researchers wrote in the report. "Though we saw less of it, malware was still stopping by for a visit, while spam traffic decided to increase in malware's absence."

Along with a spike in targeted email campaigns, particularly a bunch zeroing in on retailers and etailers, AppRiver found a number of old familiar malware campaigns -- especially scams using the IRS as a front -- were still garnering their fair share of victims.

By country, the U.S. still reigned supreme in the generation of new spam messages, accounting for just under 25 million new pieces of spam a day in October. Russia, India, the UK and Brazil rounded out the top five countries of origin for new spam messages last month.

Security experts at AppRiver and other leading security software firms said they continue to see massive phishing campaigns using the Zeus Trojan to steal passwords, logins and other personal information from people using a variety of legitimate sites including Apple's (NASDAQ: AAPL) iTunes store.

"Around midmonth, we began seeing a massive influx of messages attempting to spread the Zeus Trojan," the report said. "During that time, we saw a steady stream of messages with a huge spike in traffic."

"Cybercriminals must be finding a pretty good infection rate with unprotected users for them to continue as long as they have," researchers added. "We have seen plenty of evidence indicating people are falling for this social engineering tactic."

Larry Barrett is a senior editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.

Keep up-to-date with desktop security issues; follow eSecurityPlanet on Twitter @eSecurityP.