The exploit relies on attackers creating rogue applications to take advantage of vulnerabilities in the Android build HTC uses on some of its phones, according to a post by the United States Computer Emergency Readiness Team (US-CERT).
Users with affected phones should go to HTC's support site for software updates, US-CERT says.
The affected Android builds expose 802.1X passwords to applications on the phones that have permission to access the Wi-Fi state of the phone. The flaw doesn't allow access to the 802.1X settings themselves, it does allow viewing Wi-Fi credentials, according to a description of the flaw at the My War With Entropy blog by Bret Jordan.
So an application could gain access to stored SSIDs of Wi-Fi networks, user names and passwords. If the application also has Internet-access privileges, it could send along the stolen credentials to attackers.
If the stolen credentials are for corporate networks, they could be used to target data on those business networks, Jordan writes.
According to US-CERT, affected phones are:
• Desire HD (both "ace" and "spade" board revisions) - Versions FRG83D, GRI40
• Glacier - Version FRG83
• Droid Incredible - Version FRF91
• Thunderbolt 4G - Version FRG83D
• Sensation Z710e - Version GRI40
• Sensation 4G - Version GRI40
• Desire S - Version GRI40
• EVO 3D - Version GRI40
• EVO 4G - Version GRI40
HTC and Google were told about the flaw last September and have been working to fix the problem and arrange for public disclosure. Jordan describes the companies as responsive and good to work with.