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 opinion The Importance of Identity Management in Security By Charles Pelton Nov 28, 2023 5 mins Cybercrime Artificial Intelligence Data Management brandpost Sponsored by Rocket Software Why data virtualization is critical for business success Data is your most valuable resource—but only if you can access it fast enough to address present challenges. Data virtualization is the key. By Milan Shetti, CEO of Rocket Software Nov 28, 2023 4 mins Digital Transformation brandpost Sponsored by Rocket Software The hybrid approach: Get the best of both mainframe and cloud Cloud computing and modernization often go hand in hand, but that doesn’t mean the mainframe should be left behind. A hybrid approach offers the most value, enabling businesses to get the best of both worlds. By Milan Shetti, CEO Rocket Software Nov 28, 2023 4 mins Digital Transformation brandpost Sponsored by Rimini Street Dear Oracle Cloud…I need my own space Access results from a recent Rimini Street survey about why enterprises are rethinking their Oracle relationship and cloud strategy. By Tanya O'Hara Nov 28, 2023 5 mins Cloud Computing 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