Spammers use free Web services to shield links

Spammers are taking advantage of free Web services

Spammers are abusing free Web services to make their spam links look more legitimate, according to e-mail security vendor MessageLabs.

One of the services, a photo-hosting site called ImageShack, lets people upload different types of photo formats, including Flash files, said Paul Wood, a senior analyst with MessageLabs.

Flash files, which have the extension ".swf", can be used for animated graphics and can also be used to automatically redirect people to other Web sites. That feature can be abused.

The attack involving ImageShack works like this: Spammers upload a Flash file then copy the link for that file -- which comes from ImageShack's domain -- in a spam message. If the link is followed, the Flash file redirects the victim to a spam site, Wood said.

The technique offers an advantage for spammers. Antispam software will often scan links in e-mail and block those e-mails with suspicious-looking ones. But ImageShack's domain is considered to have a good reputation, so messages won't be blocked.

"If you start blocking on domain name only, you can incur a lot of collateral damage," Wood said.

Another more dangerous variation on this theme is a spam e-mail promoting a video. If the link is clicked, a Flash file redirects the victim to a site where a pop-up window immediately implores the user to download a codec supposedly needed to play the video file. Invariably, the file isn't a codec but some piece of malicious software.

Even if the spam link in the e-mail appears to be OK, there are many other ways to tell if a message is spam.

The header -- or batch of information that shows where an e-mail came from and the path it followed -- can be used to tell if it came from a domain that has been prone to abuse and subsequently blocked, Wood said.

Google's Picasa photo service and Yahoo's Flickr don't allow Flash files. But that hasn't exempted Picasa from abuse. Spammers use Picasa to host images, which are then incorporated into spam messages, Wood said.

Again, spammers are piggy backing on Google's good reputation. Images that are hosted on less reputable services or domains have a greater chance of being automatically blocked by security programs.

MessageLabs has also seen a similar type of abuse of Microsoft's Windows Live SkyDrive, which is an online file storage service, Wood said.

The scenario is almost the same: The link is connected with a file on SkyDrive, but then the link performs an HTML redirect to a dodgy site. SkyDrive also allows Flash files to be uploaded, offering another possible way to attack.

Join the Good Gear Guide newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection

Tags spam

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Jeremy Kirk

IDG News Service
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Armand Abogado

HP OfficeJet 250 Mobile Printer

Wireless printing from my iPhone was also a handy feature, the whole experience was quick and seamless with no setup requirements - accessed through the default iOS printing menu options.

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?