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Re: Untrusted code execution

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From Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups comp.lang.python
Subject Re: Untrusted code execution
Date Tue, 5 Apr 2016 08:50:16 -0600
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On Tue, Apr 5, 2016 at 8:17 AM, Rustom Mody <rustompmody@gmail.com> wrote:
> On Tuesday, April 5, 2016 at 7:19:39 PM UTC+5:30, Jon Ribbens wrote:
>> On 2016-04-03, Jon Ribbens wrote:
>> > I'd just like to say up front that this is more of a thought experiment
>> > than anything else, I don't have any plans to use this idea on any
>> > genuinely untrusted code. Apart from anything else, there's the
>> > denial-of-service issue.
>> >
>> > That said, is there any way that the following Python 3.4 code could
>> > result in a arbitrary code execution security hole?
>> >
>> >     tree = compile(untrusted_code, "<script>", "eval", ast.PyCF_ONLY_AST)
>> >     for node in ast.walk(tree):
>> >         if (isinstance(node, ast.Name) and node.id.startswith("_") or
>> >             isinstance(node, ast.Attribute) and node.attr.startswith("_")):
>> >                 raise ValueError("Access to private values is not allowed.")
>> >     namespace = {"__builtins__": {"int": int, "str": str, "len": len}}
>> >     print(eval(compile(tree, "<script>", "eval"), namespace))
>>
>> Nobody has any thoughts on this at all?
>
> i actually did...
>
> But dont know enough of the AST API to figure out what you are trying/avoiding etc

Same here, although it looks to me like this approach could work. Or
I'm just not clever enough to see how it could be exploited.

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Thread

Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-03 21:12 +0000
  Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 13:46 +0000
    Re: Untrusted code execution Rustom Mody <rustompmody@gmail.com> - 2016-04-05 07:17 -0700
      Re: Untrusted code execution Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-05 08:50 -0600
      Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 17:26 +0000
        Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 18:50 +0000
          Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 19:14 +0000
        Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 19:13 +0000
        Re: Untrusted code execution Steven D'Aprano <steve@pearwood.info> - 2016-04-06 11:43 +1000
          Re: Untrusted code execution Random832 <random832@fastmail.com> - 2016-04-06 09:14 -0400
            Re: Untrusted code execution Steven D'Aprano <steve@pearwood.info> - 2016-04-07 11:45 +1000
              Re: Untrusted code execution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-04-07 14:48 +1000
              Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-07 15:18 +0000
                Re: Untrusted code execution Steven D'Aprano <steve@pearwood.info> - 2016-04-08 15:28 +1000
          Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-07 12:13 +0000
            Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-07 14:25 +0000
              Re: Untrusted code execution Steven D'Aprano <steve@pearwood.info> - 2016-04-08 15:26 +1000
            Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-07 17:20 +0000
              Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-07 17:35 +0000
              Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-10 17:06 +0000
      Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 17:40 +0000
    Re: Untrusted code execution Paul Rubin <no.email@nospam.invalid> - 2016-04-05 13:39 -0700
      Re: Untrusted code execution Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-04-05 21:13 +0000
        Re: Untrusted code execution Paul Rubin <no.email@nospam.invalid> - 2016-04-07 00:08 -0700
          Re: Untrusted code execution Lele Gaifax <lele@metapensiero.it> - 2016-04-08 10:10 +0200

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