There are a few tools for executing assembly code from Python:

• CorePy
• PyAsm

But these two projects focus on actually generating assembly code from Python, presumably for performance.

This project is focus on debugging and safety. In CTFs you sometimes something disassemble a piece of code and you need to run it seperately from the rest. This module allows you to run assembly code from within Python in a totally safe environment. Hence: re-assember.

>>> import ctypes
>>> import pyreasm

>>> state = pyreasm.ReAsm("xchg rax, rbx", rax=1, rbx=2).run()
>>> print "rax=%d rbx=%d" % (state.rax, state.rbx)
rax=2 rbx=1

Here the given assembly code is assembled into a seperated program and run and the results transferred back.

You can also define variables which can also copied between the Python and the assembly program. For example:

>>> class Test(ctypes.Structure):
>>>     _fields_ = [('int_var', ctypes.c_long)]

>>> state = pyreasm.ReAsm("xchg rax, int_var", Test, int_var=1, rax=2).run()
>>> print "int_var=%d rax=%d" % (state.int_var, state.rax)
int_var=2 rax=1

Since the code is run in a separate process, you don't have to worry about crashes.

>>> try:
>>>     state = pyreasm.ReAsm("xor rax, rax\ncall rax").run()
>>> except Exception, e:
>>>     print e
Signal SIGSEGV