Users of, that is, subscribers to, Apple’s MobileMe service have found themselves getting more spam than usual, as well as some “phishing” scams aimed directly at them. And spammers are getting fewer bouncebacks.
The problem lies in the iDisk online file storage service every subscriber is provided with. The service comes with a “public” folder which cannot be hidden or deleted. Every public folder starts with the address http://idisk.mac.com/ and then it’s followed by their username and “-Public”. A programmer can write code to automatically generate random user names using words and names straight out of a digital dictionary.
“Why do this with iDisk’s public folder space?”, you ask.
iDisk: A Sample Public Folder
The username associated with a public iDisk folder is also the first half of their email address assigned to them with the MobileMe service. The second half of their address is either @me.com or @mac.com. This hack allows a spammer to determine the validity of email address. Any http://idisk.mac.com/username-Public address that doesn’t result in a “Account Error: Inactive” message — as the link above probably will — means that they’ve found a legitimate account. A legitimate account would come up with a page as shown in the picture at right.
Furthermore, if the public folder shows that there are files stored in that location, as the sample picture shows, a spammer could tailor a message referring to that file in an effort to get the user to reply and reveal personal information.
Imagine if you used this service: You upload some of your files or photos to it, and then, a few days or weeks later you get an email mentioning one or more of your files by name. If you hadn’t thought about your “public folder” being “public”, you might take the message very seriously. Even more so if the sender claimed to represent Apple. (Of course that spammer would be breaking the law by falsely identifying themselves. See my article “Spammers Get CANned”.)
Anyone Can See The Files?
Anyone can see or read the names of your public files, assuming they find your public folder, but they won’t be able to access, open, or download them unless they take a guess at your login information, too; so make sure you use a good password and not your birthday or pet’s name. They can’t upload anything to your folder either, unless they figure out your login info.
Simply said, Apple’s MobileMe iDisk service gives spammers a handy way to determine valid email addresses, so they get fewer, if any, bouncebacks and undeliverable messages. The names of files stored on iDisk could be used to make the spammer or phishers message appear legitimate.
Phishing. For those unfamiliar with this term, simply stated, it is an email message designed to get the recipient to reveal personal information such as account numbers or login information. The sender poses as well-known service or someone offering an enticement to respond. Popular targets have been eBay, PayPal, and online banking users.
In the iDisk problem discussed here, the phisher can determine if a username and email address exists. Furthermore, If the account owner stores files publicly on the service, the names of files can be referred to in a phishers email message to shore up their credibility.
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