A newly discovered flaw in all the major Web browsers could allow Internet scammers to successfully launch phishing attacks, according to a warning from security research outfit Secunia Inc.
The vulnerability, confirmed on fully patched versions of Microsoft Corp.s dominant Internet Explorer browser, can be exploited by malicious hackers to trick surfers into disclosing confidential information, including credit card and social security numbers.
“The problem is that JavaScript dialog boxes do not display or include their origin, which allows a new window to open a prompt dialog box, which appears to be from a trusted site,” Secunia said in a public advisory.
“Successful exploitation normally requires that a user is tricked into opening a link from a malicious Web site to a trusted Web site,” the company added.
Secunia has published a proof-of-concept demonstration for users to determine if their browser of choice is affected.
In the demonstration, Secunia shows that visitors to Google.com could be tricked into entering information in a JavaScript dialog that did not originate from Google Inc.
In theory, this trick could be replicated from online banking or other financial Web sites to hijack sensitive login information.
In addition to Internet Explorer (Windows and Mac), the vulnerability was also confirmed on the Mozilla, Firefox, Camino, Safari and iCab browsers.
Late Tuesday, Microsoft issued a security advisory to confirm that the issue affected its IE browser, but said it had no plans to issue a patch.
“This is an example of how current standard Web browser functionality could be used in phishing attempts,” the advisory read.
“If a particular window or dialog box does not have an address bar and does not have a lock icon that can be used to verify the sites certificate, the user is not provided with enough information on which to base a valid trust decision about the window or dialog box,” Microsoft said, urging users to follow its general guidance about how to avoid spoofing attacks.
The flaw was recently patched in the release of Opera 8.0.1, but Secunia warned that earlier versions of the Norwegian companys flagship browser may be vulnerable.
Secunias warning comes exactly one week after Microsoft shipped a “critical” cumulative IE update to fix a remote code-execution flaw that exists due to the way the browser handles PNG (Portable Network Graphics) files.
According to Secunias advisory, the bug was reported to Microsoft one month ago, on May 24.
The company recommends that surfers avoid browsing untrusted Web sites until vendor-supplied patches are available.
Editors Note: This story was updated to include information about a security advisory and confirmation from Microsoft.
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