Hands-On IoT Hacking: Rapid7 at DEF CON 30 IoT Village, Pt. 2

Welcome back to our blog series on Rapid7's IoT Village exercise from DEF CON 30. Last week, we covered the basics of the exercise and achieving access to flash memory. In this post, we'll cover how to extract partition data.

Extracting partition data

The next step in our hands-on IoT hacking exercise is to identify the active partition and extract the filesystems for modification. The method I have used for this is to examine the file date stamps – the one with the most current date is likely the current active file system.

Note: Curious why there are multiple or duplicate filesystem partitions on an embedded device? Typically, with embedded device firmware, there are two of each partition, two kernel images, and two root file system images. This is so the device's firmware can be updated safely and prevent the device from being bricked if an error or power outage occurs during the firmware update. The firmware update process updates the files on the offline partitions, and once that is completed properly, the boot process loads the new updated partitions as active and takes the old partitions offline. This way, if a failure occurs, the old unchanged partition can be reloaded, preventing the device from being bricked.

On this cable modem, we have 7 partitions. The key ones we want to work with are Partition 5, 6, 12, 13. This cable modem has two MCU:, an ARM and an ATOM processor. Partition 5 and 6 are root filesystems for the ARM processor, which is what we will be hacking. Partition 12 and 13 are for the root filesystems for the ATOM process, which controls the RF communication on the cable.

To ensure we alter the active partition, the first thing we need to do is check the date stamps on ..

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