Peter Sayer, IDG News Service
A cross-site scripting flaw in the PayPal Web site 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.
What Happens
The attack works by tricking PayPal members into following a
maliciously crafted link to a secure page on PayPal's site. Anyone
thinking to check the site's 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's blog today.
However, the URL (uniform resource locator) Internet address exploits
a flaw in PayPal's 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's 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 -- but 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' server, then prompts
the user for other personal information, Mutton said.
The Web server harvesting the personal details is hosted in Korea,
Mutton said.
Difficult to Detect
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's not genuine," he said. "It's 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't think people would intentionally use
it," he said.
"If somebody knows there's 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.
Copyright 2006 PC World Communications, Inc.
[TELECOM Digest Editor's Note: So we get back to the same advice
given by most sites: *NEVER* click on anything sent to you as
email or a web site you were not expecting. Regards your financial
affairs, *ALWAYS* manually enter the URL and with anything you are
not expecting (i.e. messages saying your account was, or may have
been 'compromised', or was 'closed', etc) consider calling the
customer service people on the phone to discuss it with them. PAT]
Peter Sayer (idg@telecom-digest.org)