I want to analyze an embedded firmware (car's ecu). My problem is, the file is compressed.
The firmware comes with a description xml file, which states that it is divided into sections and that those sections are individually compressed, using the NRV algorithm.
I did some searching, and none of the usual suspects (magic strings) are in the firmware.
The program that actually flashes the firmware over CAN is written in Java, so I tried decompiling it. That worked, but there are just definitions of functions, there is no flow, who the program is running, which values are passed to the functions, etc.
If it were usual assembler code, I'd just attach a debugger to the running program and had a look at the calls. But I do not know if this is possible in Java.
So my question is, how would I start to decompress the firmware?
I uploaded both firmware and respective xml, maybe some can nudge me in the right direction.
There are a lot of those NRV compressed files, for various ecus with different processors and architectures. So the decompression has to take place on the computer that flashes the firmware.