Security

Spam made up 90.4 percent of all e-mail traffic in June, with botnets accounting for the vast majority of those unsolicited messages, according to a new report from Symantec's MessageLabs.

Spam sent out from botnets, or networks of zombie PCs, made up 83.2 percent of unsolicited e-mail messages this month, MessageLabs said Tuesday in a statement. In May, 57.6 percent of spam was sent from known botnets, with Donbot responsible for 18.2 percent of these messages.

According to the messaging security company, the biggest botnet currently is Cutwail, which has doubled in size and output per bot since March. At its peak, Cutwail had an army of 1.5 million to 2 million active bots, but the shutdown of Californian ISP Pricewert earlier this month led to several hours of downtime for the botnet.

Cutwail, however, bounced back within hours, noted MessageLabs. It currently has an output of around one-third of its original capacity. Other major botnets include Rustock, Grum, Donbot, Bagle, Xarvester, Mega-D, Gheg, Asprox, and Darkmailer.

Also in June, there were an average of 1,919 new Web sites per day harboring malware and other potentially unwanted programs including spyware and adware. This represented an increase of 67 percent over May.

Over half, or 58.8 percent, of all Web-based malware that MessageLabs intercepted during the month was new, a month-on-month increase of 24.6 percent.

Data from MessageLabs also shows that more hyperlinks in instant messaging conversations are stepping stones to "instant malware."

In June, 1 in 78 hyperlinks found in instant messages linked to Web sites hosting malicious content, compared with 1 in 200 at the end of 2008. The hidden malware typically tries to perform a drive-by attack on a vulnerable Web browser or browser plug-in, said the company.

One in 80 IM users, predicted MessageLabs, may receive a malicious instant message each month.

Vivian Yeo of ZDNet Asia reported from Singapore.

Spam now accounts for 90.4 percent of all e-mail, according to a report released Monday from security vendor Symantec. This means that 1 out of every 1.1 e-mails is junk. The report also notes that spam shot up 5.1 percent just from April to May.

Spam on the rise.

(Credit: MessageLabs)

Symantec's May 2009 MessageLabs Intelligence report reveals other disturbing trends, as well. Rather than just hijack disreputable Web sites, cybercriminals now favor older and well-established domains to host their malware. The report says 84.6 percent of all domains blocked for malicious content are more than a year old. One type of domain now especially vulnerable to threats is social networking, since most of the sites' content is created by users.

"Spammers using better-known and thus more widely trusted Web sites to host malware is reminiscent of the spammers who rely on well-known Web mail and social networking environments to host spam content," said Paul Wood, Symantec's MessageLabs Intelligence senior analyst. "The trustworthy older domains can be compromised through SQL injection attacks while newer sites are more likely to be flagged as suspicious--a temporary site set up with the sole purpose of distributing spam and malware--and thus faster to get shut down."

Where you live also determines when you're spammed, says the report. For people in the U.S., spam hits its peak between 9 a.m. and 10 a.m. and then drops overnight. Europeans get a solid stream of spam throughout the day, while users in Asia-Pacific countries find most spam waiting for them in the morning. One reason for this trend, says the report, is that most spammers are at their busiest during U.S. working hours.

The popular CAPTCHA program, which asks the user to type in a series of random characters, is no longer proving as effective as once hoped. Many Web sites have relied on CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) to ensure that accounts are created by actual human beings.

But criminals have now succeeded in generating profiles with random names, apparently by using automated CAPTCHA breakers. The report notes that some major Web sites are now exploring other ways to block automated accounts, such as using photographic images that a user must analyze.

Spam levels had dropped for a short while last year after the closure of several malware-hosting Internet providers. But spammers have since bounced back from those losses by rebuilding their networks.

Symantec's MessageLabs Intelligence gathers research on spam and other malware from global data centers that track e-mails and Web pages. Symantec releases a new intelligence report each month.

Spam decreased 8 percent during September, according to a report (PDF) released Monday by MessageLabs.

Among other reasons behind the decrease, the security company cited the apparent demise of California-based Intercage, an Internet service provider alleged to have possibly been used to host command and control servers for various botnets. Intercage's upstream provider, Pacific Internet Exchange, terminated service on September 20; a second upstream provider, UnitedLayer, then terminated service on September 25. During this period, MessageLabs reported a marked decrease in spam traffic.

The impact of the Intercage ISP disconnection on botnet spam relays can be seen in this graph.

(Credit: MessageLabs)

Looking deeper into the spam traffic itself, MessageLabs found that 85 percent of sexually explicit e-mail spam is sent during the workday. A healthy 28 percent of that is sent during the lunch hours, from 11 a.m. to 1 p.m. local time. Almost all of this is blocked by corporate filters.