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Researcher Discloses Potential Internet Explorer XSS Zero-Day Flaw

A security researcher has publicly discussed a new potential zero-day vulnerability in Microsoft's Internet Explorer through the Full-Disclosure mailing list.

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Zero Day Disclosure 2

Security researcher David Leo publicly disclosed a new potential zero-day security issue on Jan. 31 that Microsoft is set to patch with a future update.

The zero-day issue was revealed on the Full-Disclosure mailing list which has been active since 2002 as a home for researchers to announce and discuss issues. The Full-Disclosure list was actually shut down for a week in 2014 after the list's original maintainer decided to pull the plug.

The new flaw detailed by Leo is what is known as a cross-site scripting, or XSS, vulnerability. According to Leo's post, he first notified Microsoft of the issue on Oct. 13, 2014.

"Attackers can steal anything from another domain and inject anything into another domain," Leo wrote.

Microsoft isn't too worried about the XSS issue since it has implemented measures in IE to help mitigate the risk.

“To successfully exploit this issue, an adversary would first need to lure a person, often through trickery, such as phishing, to a malicious Website that they’ve created," a Microsoft spokesperson stated in an email to eWEEK.

The spokesperson noted that SmartScreen, a technology that runs by default in newer versions of Internet Explorer, helps protect against phishing Websites.

Though the XSS vulnerability was first reported to Microsoft back in October 2014, the company says it's not impacting Microsoft's customers yet.

"We’re not aware of this vulnerability being actively exploited and are working to address it with an update," Microsoft's spokesperson stated. "We continue to encourage customers to avoid opening links from untrusted sources and visiting untrusted sites and to log out when leaving sites to help protect their information."

The fact that a researcher decided to publicly post the issue to a public mailing list prior to a patch being made available is something that Microsoft has had to deal with on several occasions in 2015. Google has its own policy of disclosing flaws 90 days after it reports them to a vendor and has publicly disclosed multiple Microsoft zero-days so far in 2015.

"We continue to believe that security researchers should engage with software companies to privately disclose vulnerabilities and work together to further protect customers," the Microsoft spokesperson stated.

Sean Michael Kerner is a senior editor at eWEEK and Follow him on Twitter @TechJournalist.

Sean Michael Kerner

Sean Michael Kerner

Sean Michael Kerner is an Internet consultant, strategist, and contributor to several leading IT business web sites.