If you own a mobile phone made by HTC and connect using Bluetooth, there's a decent chance security researcher Alberto Moreno Tablado can rummage through sensitive files stored on the device using a critical bug in some of its wireless device features.
The directory traversal flaw resides in the File Transfer Profile (OBEX FTP) service that's built in to the Bluetooth stack implemented by HTC, Tablado writes here. It allows an attacker to move from a phone's Bluetooth shared folder into other folders and affects HTC handsets running versions 6 and 6.1 of the Microsoft Mobile operating system.
"Microsoft states this is a 3rd party driver developed by HTC and installed on HTC devices running Windows Mobile, so the vulnerability only affects to this vendor specifically," Tablado says. "A remote attacker (who previously owned authentication and authorization rights) can use tools like ObexFTP or gnomevfs-ls from a Linux box to traverse to parent directories out of the default Bluetooth shared folder by using ../ or ..\\ marks."
Getting the required authentication or authorization rights may be easier than it sounds. Paring the HTC handset with a Bluetooth device should do the trick, but more sophisticated techniques will also work. They include sniffing the Bluetooth pairing, cracking the linkkey or spoofing the MAC address. Once the needed privileges are acquired, an attacker can remotely read or overwrite virtually any file stored on the device in a way that's completely transparent to the victim.
Tablado says he first notified HTC of the bug in February. "However, I only received acknowledgement responses from HTC Europe Support (Tech), no intentions to release a security fix from HTC Taiwan. Therefore, having attempted to collaborate with the vendor, I am forced to go public with all the information yet undisclosed."
A spokesman for HTC America didn't immediately return a phone call seeking comment for this article. ®