Re: CVE Request: Insecure Software Download in pip

[Donald Stufft <donald () stufft io>]

On Jul 30, 2013, at 2:21 AM, Kurt Seifried <kseifried () redhat com> wrote:

> Signed PGP part
> On 07/27/2013 01:10 AM, Donald Stufft wrote:
> > On Jul 27, 2013, at 3:08 AM, Kurt Seifried <kseifried () redhat com>
> > wrote:
> >
> > > On 07/25/2013 03:09 AM, Donald Stufft wrote:
> > > > I'd like to request a CVE for pip 
> > > > (https://pypi.python.org/pypi/pip/).
> > > >
> > > > The mirroring support (-M, --use-mirrors) was implemented
> > > > without any sort of authenticity checks and is downloaded over
> > > > plaintext HTTP. Further more by default it will dynamically
> > > > discover the list of available mirrors by querying a DNS entry
> > > > and extrapolating from that data. It does not attempt to use
> > > > any sort of method of securing this querying of the DNS like
> > > > DNSSEC. Software packages are downloaded over these insecure
> > > > links, unpacked, and then typically the setup.py python file
> > > > inside of them is executed.
> > > >
> > > > The vulnerable code is located at: - 
> > > > https://github.com/pypa/pip/blob/develop/pip/index.py#L60-L64
> > > > - 
> > > > https://github.com/pypa/pip/blob/develop/pip/index.py#L205-L207
> > > > - 
> > > > https://github.com/pypa/pip/blob/develop/pip/index.py#L553-L572
> > > > - 
> > > > https://github.com/pypa/pip/blob/develop/pip/index.py#L999-L1024
> The affected versions are every released version since 0.8.1 which
> > > > are: 0.8.1, 0.8.2, 0.8.3, 1.0, 1.0.1, 1.0.2, 1.1, 1.2, 1.2.1,
> > > > 1.3, 1.3.1, 1.4
> > > >
> > > > I'm not aware of this issue having ever had a CVE requested for
> > > > it and my attempts to search the CVE database did not appear to
> > > > turn up anything relevant but the search doesn't appear to be
> > > > the greatest so I may have missed it.
> > > >
> > > > I'm hoping to land a patch for this in a future release
> > > > (current iteration of patch available at 
> > > > https://github.com/dstufft/pip/compare/remove-mirror-support)
> > > > but there is no planned fix version as of yet.
> > > >
> > > > ----------------- Donald Stufft PGP: 0x6E3CBCE93372DCFA //
> > > > 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
> > >
> > > Was it supposed to be secure (like was this explicitly supposed
> > > to be all encrypted/etc.)? This sounds more like security
> > > hardening than a security vulnerability.
> > >
> > > - -- Kurt Seifried Red Hat Security Response Team (SRT) PGP:
> > > 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
> >
> > The mirroring protocol explicitly included provisions for
> > verification which was not being done.
> >
> > http://www.python.org/dev/peps/pep-0381/#mirror-authenticity
> >
> > ----------------- Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B
> > 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA
>
> So to confirm, we're talking about the line:
>
> "Verification is not needed when downloading from central index, and
> should be avoided to reduce the computation overhead."
>
> So accessing the central index is done over HTTP by default, no
> support for HTTPS previous to commit
> https://github.com/pypa/pip/commit/e80c387a26858c4d7ff43c5f030b04b03fd43dfe
> correct?
>
> - -- 
> Kurt Seifried Red Hat Security Response Team (SRT)
> PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993

The central index is pypi.python.org and historically (and at the time of that commit) it was
not accessed securely (plaintext HTTP, no authenticity checks etc). The mirroring support,
(located at, a.pyp.python.org, b.pypi.python.org, …) which that commit adds and PEP381
deals with, was supposed to have authenticity checking preventing a malicious mirror
operator from attacking you by checking a html manifest that included hashes was signed
by a key owned by the central index (pypi.python.org). That commit does not include
checking that the mirrors are not hosting content that differs from the central index.

So basically the lack of authenticity checking when installing directly from the central index
is a separate issue which has been (mostly) addressed with pip 1.3, and more so with 1.4. 
However this request deals explicitly with the implementation of the protocol for installing
from the hosts that mirror the central index, but are not the central index.

For what it's worth my PR to fix it is here https://github.com/pypa/pip/pull/1098

Between myself, the comment on the PR, and the mailing list I have 3 pip developers +1ing
the change so it's likely it's going to land unless one of the others has concerns.

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

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