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[CTF] Reversing using angr (flag via args)
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| #!/usr/bin/env python3 | |
| # -*- coding: utf-8 -*- | |
| import pdb | |
| import sys | |
| import angr | |
| import claripy | |
| argc, argv = len(sys.argv), sys.argv | |
| if argc != 3: | |
| print(f"usage: {argv[0]} [exec-file] [flag-length]") | |
| sys.exit(-1) | |
| EXEC_FILE_PATH = sys.argv[1] | |
| FLAG_LENGTH = int(sys.argv[2]) | |
| p = angr.Project(EXEC_FILE_PATH, load_options={'auto_load_libs': False}) | |
| flag_chars = [claripy.BVS('flag_%d' % i, 8) for i in range(FLAG_LENGTH)] | |
| flag = claripy.Concat(*flag_chars) | |
| state = p.factory.full_init_state( | |
| args=[EXEC_FILE_PATH, flag], | |
| add_options=angr.options.unicorn | |
| ) | |
| for c in flag_chars: | |
| state.solver.add(c >= 0x20) | |
| state.solver.add(c <= 0x7e) | |
| simgr = p.factory.simulation_manager(state) | |
| simgr.explore(find=lambda s: b"correct" in s.posix.dumps(1)) | |
| print(simgr.found[0].solver.eval(flag, cast_to=bytes)) |
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