files's binary data stored as variable inside python file

Question

Lets say a have program.exe , i will create a python script that will

read program.exe in binary mode and save it in variable data
open mypytonprog.py in binary append mode
append data to mypythonprog.py (?)

before this, mypythonprog.py would be prepared as:

program_data='''

after it, mypythonprog.py would continue as:

'''
programs continues....

(i want somehow to put that program code into a program_data variable)

This, does not work,of course, but can it be done in some way ? What i want basicly is: mypythonfile.py to be able to create an exe file with binary data stored inside it.

I suppouse i have to encode that data to a shellcode to by able to put it inside mypythonfile.py,
right ?

Ignacio Vazquez-Abrams · Accepted Answer · 2011-02-06 03:51:57Z

3

>>> 'some binary data'.encode('base64')
'c29tZSBiaW5hcnkgZGF0YQ==\n'
>>> 'c29tZSBiaW5hcnkgZGF0YQ==\n'.decode('base64')
'some binary data'

answered Feb 6, 2011 at 3:51

Ignacio Vazquez-Abrams

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Hugh Bothwell · Accepted Answer · 2011-02-07 23:50:59Z

2

import base64

exe = 'c:/users/me/program.exe'
script = 'c:/users/me/newpython.py'
chunksize = 6144
linelength = 80

with open(exe,'rb') as inf, open(script,'w') as outf:
    outf.write('program_data = """')

    while True:
        progdata = inf.read(chunksize)
        if len(progdata):
            progdata = progdata.encode("base64")
            outf.writelines(progdata[i:i+linelength] for i in range(0, len(progdata), linelength))
        else:
            break

    outf.write('""".decode("base64")')

Edit:

The idea is to process the input file in convenient chunks rather than reading a potentially-huge file into memory.

After base64-encoding the chunk, I then split it into 80-char lines (this is basically just to keep it manageable in the text editor) and write it to output.

I wrap the data in program_data = """ .. """.decode("base64") such that when Python loads the file, the data will be automatically decrypted - program_data will contain the binary data you desire.

8096 was a brain fart - I meant to use 8192 bytes (8KB). Then I realized there was a second problem; encoding a chunk other than a multiple of 3 chars long results in '='-padded output, which prematurely truncates decoding. I have changed the chunk size to 6KB = 512 bytes (default NTFS block size) * 3 chars * 4 (arbitrary multiple); this seems to work as expected.

Hope that helps!

edited Feb 7, 2011 at 23:50

answered Feb 6, 2011 at 4:29

Hugh Bothwell

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2 Comments

Kristian Over a year ago

well, this is surely better than @Ignacio answer ( it doesnt give me any arrors....about non-ASCII charracters...) but when i write that program_data in (binary?) mode to file ( and close is) windows gives me an arror that it isnt a valid Win32 aplication....

Kristian Over a year ago

could you descire a bit what is it doing ? why chunksize = 8096 ? i see what it is doing, but why ? what is your stategy ? :-) thx

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