A cross-site scripting flaw in the PayPal website allows a new phishing attack to masquerade as a genuine PayPal log-in page with a valid security certificate, according to security researchers.Fraudsters are exploiting the flaw to harvest personal details, including PayPal log-ins, Social Security numbers and credit card details, according to staff at Netcraft, an Internet services company in Bath, England. The PayPal site, owned by eBay, allows users to make online payments to one another, charged to their credit cards, and log-in credentials for the service are a prized target of fraudsters.The attack works by tricking PayPal members into following a maliciously crafted link to a secure page on PayPal\u2019s site. Anyone thinking to check the site\u2019s security certificate at this point will see that it is a valid 256-bit certificate belonging to the site, Netcraft employee Paul Mutton wrote in the company\u2019s blog on Friday.However, the URL exploits a flaw in PayPal\u2019s site that allows the fraudsters to inject some of their own code into the page that is returned, he wrote. In this case, the result is a warning that the user\u2019s account may have been compromised, and that they "will now be redirected to Resolution Center."The page to which they are redirected asks for their PayPal account details\u2014but thanks to the cross-site scripting flaw in the PayPal site, and the data injected into the URL by the fraudsters, the page is no longer on the PayPal site. Instead, the page steals the log-in details and sends them to the fraudsters\u2019 server, then prompts the user for other personal information, Mutton said.The Web server harvesting the personal details is hosted in Korea, Mutton said.The cross-site scripting technique makes the phishing attempt difficult to detect, said Mike Prettejohn, also of Netcraft.If the malicious link arrived by e-mail, then "there would be clues in the mail that it\u2019s not genuine," he said. "It\u2019s a technique chosen by fraudsters because it is hard to spot."Although there could be benign uses of cross-site scripting to transfer data between sites, the technique has an inherent security risk, Prettejohn said. "I don\u2019t think people would intentionally use it," he said."If somebody knows there\u2019s a cross-site scripting opportunity on their site, the right thing to do would be to fix it," he said.Staff at PayPal could not immediately be reached for comment.-Peter Sayer, IDG News Service (Paris Bureau)Related Links:How to Foil a PhishFoiling PhishingKeep checking in at our CSO Security Feed page for updated news coverage.