A researcher known for unlocking Motorola handsets, has leveraged a vulnerability in the TrustZone kernel to bypass the bootloader restrictions on several devices sold by Verizon.
The devices that have been proven vulnerable are the Motorola Razr HD, Razr M, and Atrix HD devices. According to the researcher, as well as a NVD outline, the Qualcomm MSM8960 chipset doesn’t verify the association between a physical address argument and a memory region. Thus, a user can unlock bootloader using specially crafted SMC operations.
However, the tools needed have already been released to the public, making the task of exploiting the flaw easily accomplished by anyone who desires an unlocked device. Dan Rosenberg, the researcher who discovered the kernel flaws, described his process in a blog post last week.
“At this point, the end was in sight, but I knew I would need a vulnerability in the TrustZone kernel in order to set this flag (0x2) to zero, allowing my SMC call to blow the QFuse required to unlock the bootloader,” he remarked.
“Fortunately, I didn’t have to look long, since one of the other SMC commands in the same section of the TrustZone kernel contains a fairly obvious arbitrary memory write vulnerability…”
While important, and certainly something that needs fixed, the vulnerability that Rosenberg discovered isn’t earth shattering to the enterprise. However, it’s important to remember that should an employee have an unlocked (rooted) device, and use the tools recently made available to unlock the bootloader, then that could cause problems with MDM solutions or other corporate applications.
Additional details are available here.