A new threat is affecting the famous Yahoo Mail and Hotmail, two of the most popular email solutions on the Internet. BitDefender Labs identified the threat as Trojan.Spammer. HotLan.A, the security company saying that it tries to use the mail accounts to send million of spam messages. However, its working procedure is quite complex because it automatically generates new email accounts and, using the email addresses discovered on multiple websites, it sends unsolicited messages to all emails. The numbers are at least shocking: 500 new accounts created every hour and 15,000 Hotmail accounts used for spam.

"There are only about 500 or so new accounts being created every hour," commented head of BitDefender Antivirus Lab Viorel Canja. "But still, we've seen 15,000+ Hotmail accounts being used so far. It's hard to estimate how many spam e-mails have already been sent."

The most interesting matter of this new dangerous campaign is the way the Trojan horse manages to create new mail accounts since both services, Yahoo and Hotmail, are protected with visual captchas. Those security tools are requiring users to enter the codes shown in an image, so it's quite difficult to create a script able to bypass this protection.

If the attackers were able to build a software solution meant to bypass the visual captchas, it is an obvious sign that the security of our computers is threatened and there's not much to do to defend ourselves. However, you're recommended to use very complex passwords and avoid opening untrusted or unsolicited email messages coming into your inbox.

Also, you can use a powerful antispam solution to protect your account as well as avoid publishing your email address on public websites because the attackers might use it for spamming. Following the recent reports, you can get your account suspended in no time because the parent companies are quickly closing the dangerous email addresses in order to stop the spamming campaigns.