Hackers exploiting the software flaw in Microsoft Corp.'s Internet Explorer Web browser have so far attacked government agencies, defense contractors, energy companies and banks, CNNMoney reported.


The cybersecurity firm FireEye, which originally revealed the flaw, said on Thursday that there are already victims despite Microsoft having issued a fix.


FireEye also spotted that hackers are specifically targeting older computers running on Windows XP, and those with the Internet Explorer 8 version of the browser.


Microsoft announced Thursday that it had fixed the glitch and that most users will not have to take any action, as the fix will be downloaded automatically, according to this article in Time. But customers who haven't enabled automatic updates are encouraged to apply the update manually as soon as possible.


The CNNMoney article warns that there are potential real-world risks with the recent security breaches that include the Internet Explorer hack, the Heartbleed bug and an AOL hack in April.