Adam Biviano, senior systems engineer at Trend Micro Australia and New Zealand, said it would be difficult for most users to tell the difference between the authentic Yahoo site and the newly emerged forgery.
"It is pretty much identical to the original from a look and feel point of view. An end user is not going to be able to tell the difference between this one and the real thing," said Biviano.
Biviano believes victims could be lured to the site using a diverse range of methods, including the use of a virus, Trojan horse, e-mail or even by 'poisoning' the domain name server (DNS).
"It is hard to find out [how the link] is being sent out. The [Web site] may be set up to be ready for a pharming-type attack where the DNS has been affected," said Biviano.
DNS cache poisoning involves the practice of hacking into domain name servers and replacing the numeric addresses of legitimate Web sites with the addresses of malicious sites.
Regardless of how a victim ends up at the site, once they arrive, they are instructed to log into their account by entering a username and password.
Trend Micro warns that another danger posed by this type of site is that a number of vulnerabilities have been discovered in the way browsers process photographs.
"There was a case where some browsers were vulnerable. This allowed code to be executed through the browser just by viewing a JPEG. Microsoft patched this quite quickly afterwards but as is usual the threat lingers for a long time because there are machines out there that are not patched," said Biviano.
A Yahoo spokesperson told ZDNet Australia that Yahoo is committed to taking appropriate action swiftly, but because of the company's privacy policy, it is "not able to comment on specific cases."
This is the second time Yahoo has been targeted by phishers in just over a month. In August, Trend Micro warned of a Web site mimicking a Yahoo service offering free games.
