In angr, how to Load and Analyze a binary file that only contains function instructions, not a ELF file

Question

I have some binary files, each of them contain instructions of a function, (may be a little more in the end). The begining of the file is also the start point of the function.

This files were extracted from a ELF file.The platform is arm64.

So, how to load and analyze this file using angr?

The target:

Every function has a "switch case statement", the target is to get all intergers of the case expression.

Example(C code):

void func1(int cmd){
    switch (cmd) {
    case 1:
        xxxx
        break;
    case 10:
        yyyy;
        break;
    }
}

Result: 1,10

Alberto · Accepted Answer · 2017-07-31 09:11:58Z

1

my suggestion is to not use angr in this case because you could extract all the cases in a much easier way for example using r2pipe. I've create a simple example for you and I hope it helps.

C code

int main(int argc, char* argv[]) {

    switch(argc) {
        case 1:
            break;
        case 2:
            break;
        default:
            break;
    }

}

python script

import r2pipe

r2 = r2pipe.open("switch")

r2.cmd("aa")

r2.cmdj('s main')
instructions = r2.cmdj('pdfj')

for instruction in instructions['ops']:
    if ( instruction["type"] == "cmp" ):
        print instruction["ptr"]

Output:

r2pipe.cmdj.Error: No JSON object could be decoded
1
2

I'm not sure what I had that error message at the beginning of the output.

HTH

answered Jul 31, 2017 at 9:11

Alberto

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