JeromePetazzoni :: DerniersChangements :: DerniersCommentaires? :: ParametresUtilisateur :: :: Vous êtes

By modifying the MTD map driver (responsible for mapping the root filesystem into /dev/mtdblock0, thus allowing it to be used as the root fs!), I could access the whole flash memory of my router. It was very simple, and it allows to dump the whole firmware, that is :

You can download the source and compiled module (compile it like the module in the KernelChmod trick) ; once the module is loaded, you should be able to access /dev/mtdblock1 and dump it ; for instance, I used the netcat of a cross-compiled busybox (binary available here) and did busybox nc -l -p 1234 < /dev/mtdblock1, then on my PC nc 1234 > flashdump. Wait a bit, and you have your flash image.

Splitting the firmware image into its components is very easy : the first 64KB is the CFE bootloader ; then there's a "header" telling the size of the root filesystem and the kernel. The remaining part is yet to be decoded.
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