Re: Requesting CVE-ID(s) for Python's pip

[Donald Stufft <donald () stufft io>]

On Jul 30, 2013, at 2:29 AM, Kurt Seifried <kseifried () redhat com> wrote:

> Signed PGP part
> On 07/26/2013 09:46 AM, Donald Stufft wrote:
> > On Jul 26, 2013, at 8:03 AM, isis agora lovecruft
> > <isis () torproject org> wrote:
> >
> > > I would also like to request CVE assignment(s) for two issues in
> > > pip (https://github.com/pypa/pip/), related to Donald Stufft's.
> > >
> > > First issue: ------------ Python's pip versions 1.4.x and earlier
> > > are vulnerable to an Arbitrary Code Execution Attack due to
> > > incorrect regexp parsing of external download links in the
> > > following functions in pip/index.py:
> > >
> > > * PackageFinder._get_pages()
> > > https://github.com/pypa/pip/blob/1.3.X/pip/index.py#L232 *
> > > PackageFinder._sort_links()
> > > https://github.com/pypa/pip/blob/1.3.X/pip/index.py#L272 *
> > > PackageFinder._package_versions()
> > > https://github.com/pypa/pip/blob/1.3.X/pip/index.py#L285 *
> > > PackageFinder._link_package_versions()
> > > https://github.com/pypa/pip/blob/1.3.X/pip/index.py#L290
> > >
> > > Which allow an attacker with the ability to Man-in-the-Middle
> > > external package URIs (which often include external HTTP URIs,
> > > and can include the module author's personal website, see 
> > > https://github.com/pypa/pip/commit/a3584d176697bd4c83390de1857679d44389e00d#L0L265)
> to specify an arbitrarily high package version number and gain code
> > > execution.
> > >
> > > Uptream bugtracker reports:
> > > https://github.com/pypa/pip/issues/425#issuecomment-20639993 
> > > https://github.com/pypa/pip/issues/425#issuecomment-20640890
> > >
> > > Other mentions:
> > > https://github.com/pypa/pip/commit/9ccd5f0bb37508f03e6a19be58af7384eede2157
> https://paste.debian.net/7309/
> > > This issue is fixed in pip>=1.5.x by Donald Stufft in the
> > > following commits: 
> > > https://github.com/pypa/pip/commit/0e1da584f418ae0088b43d01248572e2ff53d3a1
> https://github.com/pypa/pip/commit/9ccd5f0bb37508f03e6a19be58af7384eede2157
> > I'm not sure I understand this one. Is this just the external urls?
> > Technically it wasn't a problem with the regexp's they worked fine.
> > It was just bad behavior inherited from legacy systems. 1.4.x
> > defaults to allowing them but enables people to turn them off,
> > 1.5.x will disallow them by default.
> >
> > 1.3.x and earlier allowed them and offered no way to disable them.
>
> So it sounds like 1.3.x was definitely vulnerable to this with no way
> to disable it, 1.4 was vulnerable by default but could be made safe,
> and 1.5 is vulnerable but safe by default, is that correct?

Yes, assuming this is the unverified external link problem which I believe
it is, except 1.5 is a future version that hasn't happened yet so it's "will" b
 safe by default. As a pip developer, again assuming my understanding
of the request is correct, I do believe a CVE is warranted here.

> > > Second issue: ------------- Python's pip versions 1.5.x and
> > > earlier use MD5 hashes for verification of package integrity
> > > against PyPI (which defaults to providing MD5).
> >
> > Strictly speaking pip doesn't default to any hash. It just uses the
> > hash given to it. Prior to 1.2 it only allowed MD5 but since the
> > release of 1.2 it has allowed any of the guaranteed hashes in
> > python's hash lib.
> >
> > See: https://github.com/pypa/pip/pull/467
> >
> > Setuptools has also historically only allowed MD5 but has recently
> > with version 0.9+ enabled similar abilities to setuptools to enable
> > the use of any available hashes as well. Distribute (a fork of
> > setuptools which has now been merged back into setuptools) only
> > supports MD5 in it's older releases.
>
> I'm not sure in this case MD5 alone is a security vulnerability, I
> think previously it had been decided that just because it uses MD5
> wasn't ernough to get a CVE, it had to have some specific use that
> made MD5 a problem. OTOH DES is at this point worthy of a CVE since
> you can crack it in a reasonable amount of time on AWS/etc for a few
> hundred bucks or less. Personally I would assign a CVE to everything
> using MD5 by default to try and help kill it off, but that would be a
> lot of CVEs.

This one is the one I'm not really sure about. Pip has supported any hash for
longer then they've offered verified downloads so it's certainly not a problem
there (or rather if it is a problem it's overshadowed by the fact that it wasn't
using TLS or if people manually configured it to do so it wouldn't' verify it).

Setuptools did only support MD5 until recently (and has versions that both
support TLS verification and only MD5 as a hash) however that doesn't
really buy anything until the index server serves a different hash. Currently
PyPI (which I'm also an admin on) continues to serve MD5 and going by
the thread on that discussion list it appears it will continue to do in the future.

> > ----------------- Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B
> > 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
>
>
> - -- 
> Kurt Seifried Red Hat Security Response Team (SRT)
> PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993


-----------------
Donald Stufft
PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA

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