Spam is again on the rise, led by a flood of junk images that spammers have crafted over the past few months to trick e-mail filters, according to security vendors.Called “image-based” spam, these junk images typically do not contain any text, making it harder for filters that look for known URLs or suspicious words to block them.Instead of a typed message, users will see only an embedded .gif or .jpeg image file urging them to buy pharmaceuticals or invest in penny stocks.Antispam vendor Cloudmark says that half of the incoming spam is now image-based on the “honeypot” systems it puts out on the Internet to lure spammers. “About a year and a half ago we started seeing a little bit of it, but it wasn’t until the past six months that it became a serious issue for many antispam companies,” said Adam O’Donnell, a senior research scientist with the company. Image-based spam has jumped from about 1 percent of all spam messages in June 2005 to around 12 percent today, according to Craig Sprosts, senior product manager with IronPort Systems.Its growth is helping to fuel a global resurgence in spamming, Sprosts said. The total number of spam messages sent daily is up 40 percent since April, Sprosts said. Much of this new spam is coming from a “relatively small group of spammers with control over very large zombie networks” of hijacked computers, he said.Spammers now generate an estimated 55 billion messages per day, according to IronPort. A year ago, that number was 30 billion e-mail messages per day.The combination of greater volume and better techniques has meant more complaints for network administrators.“I’ve had users complaining in the last few weeks about the overall increase in spam, and I’ve personally noticed an increased rate of spam and an increase in the percentage of it that’s image-based,” said Jonathan Forster, computing manager with the University of Arizona’s Psychology Department.Administrators at Avnet have started stripping certain embedded image files out of all messages, after seeing an uptick in image-based spam two months ago, said Rob Kudray, manager of messaging services with the computer distributor.One other tactic that is helping keep inboxes full is the spammers’ practice of constantly registering new domains. Of the 35 million domains registered in April, 32 million were never paid for and expired after five days, Sprosts said. He believes that many of those domains were used by spammers to send out their unsolicited e-mail during that five-day grace period. This technique makes it very difficult to blacklist e-mail based on the URLs it contains. “Traditional blacklists and whitelist approaches just can’t keep up with how fast they’re registering new domains and changing the URLs in the e-mail,” Sprosts said.-Robert McMillan, IDG News Service (San Francisco Bureau)Check out our CIO News Alerts and Tech Informer pages for more updated news coverage. Related content News Amazon to lay off 9,000 more workers, including some at AWS The latest round of Amazon layoffs will impact AWS, Twitch, advertising and PXT, CEO Andy Jassy said. By Jon Gold Mar 20, 2023 3 mins Technology Industry Cloud Computing BrandPost What’s next for network operations Broadcom: 2023 Tech Trends That Transform IT By Serge Lucio, Vice President and General Manager, Agile Operations Division Mar 20, 2023 8 mins IT Leadership Networking BrandPost Digital transformation obstacles: Stubborn challenges, what to do about them Value Stream Management is an increasingly essential approach to strategic transformation initiatives. To help teams more fully capitalize on the opportunities it presents, Broadcom is holding its third annual VSM Summit. By Marla Schimke, Head of Product and Growth Marketing, Broadcom's Enterprise Software Division Mar 20, 2023 3 mins Devops Software Development Feature CEO directives: Top 5 initiatives for IT leaders As organizations change course with economic gyrations, collaboration between IT and business becomes priority No. 1 for CEOs. By Stacy Collett Mar 20, 2023 7 mins IT Leadership Podcasts Videos Resources Events SUBSCRIBE TO OUR NEWSLETTER From our editors straight to your inbox Get started by entering your email address below. Please enter a valid email address Subscribe