A new wave of Trojan attacks are being unleashed from thousands of new Hotmail and Yahoo e-mail accounts.
Internet security software firm BitDefender has issued a warning that the Trojan.Spammer.HotLan.A threat is bypassing Microsoft and Yahoo security systems.
BitDefender says the Trojan uses automatically-generated accounts, suggesting that spammers have found a way to bypass captcha systems, whereby new accounts are not created until the creator states correctly which letters are depicted in an image.
Every active copy of the Trojan accesses an account, then pulls encrypted spam e-mails from a website, decrypts them and sends them to addresses taken from yet another website.
"There are 500 or so new accounts being created every hour," said head of BitDefender Antivirus Lab Viorel Canja. "We've seen 15,000-plus Hotmail accounts being used so far. It's hard to estimate how many spam e-mails have already been sent."
Canja was speaking at the end of last week, when the Trojan outbreaks were first discovered.
The spam e-mail currently being distributed is trying to lead users to a site that advertises pharmacy products, said BitDefender.
Common spammer techniques are used in the e-mail body, such as anti-bayesian security poisoning and a random e-mail subject.
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