Bug 1631420 (CVE-2018-1000802)

Summary:	CVE-2018-1000802 python: Command injection in the shutil module
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	adev88, bkabrda, cstratak, dmalcolm, hhorak, jeffrey.ness, jorton, kevin, mcyprian, mhroncok, pviktori, python-maint, rkuska, security-response-team, shcherbina.iryna, slawomir, TicoTimo, tomspur, torsava
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	It was discovered that the shutil module of python does not properly sanitize input when creating a zip file on Windows. An attacker could use this flaw to cause a denial of service or add unintended files to the generated archive.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-10-10 07:33:46 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1631421, 1631662
Bug Blocks:	1631422

Description Andrej Nemec 2018-09-20 14:32:08 UTC

A command injection vulnerability was found in the shutil module (make_archive function) of Python that can result in Denial of Service or Information leak.

Upstream issue:

https://bugs.python.org/issue34540

Upstream patch:

https://github.com/python/cpython/pull/8985/commits/add531a1e55b0a739b0f42582f1c9747e5649ace

Comment 1 Andrej Nemec 2018-09-20 14:33:00 UTC

Created python26 tracking bugs for this issue:

Affects: fedora-all [bug 1631421]

Comment 2 Miro Hrončok 2018-09-20 18:59:32 UTC

While python26 is not impacted, python2 actually is.

Here's a PR: https://src.fedoraproject.org/rpms/python2/pull-request/26

Comment 3 Andrej Nemec 2018-09-21 08:43:39 UTC

Created python2 tracking bugs for this issue:

Affects: fedora-all [bug 1631662]

Comment 4 Riccardo Schirone 2018-10-05 07:47:54 UTC

Hi Miro,

Why are you saying that python2 is affected on Fedora?
I'm asking because I wasn't able to reproduce this flaw on Linux and I believe it can be triggered on Windows only. Do you have more information on this?

Comment 5 Miro Hrončok 2018-10-09 13:00:57 UTC

Oh. I only meant that the code is in 2.7, I haven't checked that the flaw is actually usable or Python 2.7 on Linux vulnerable.

Comment 6 Riccardo Schirone 2018-10-10 07:33:46 UTC

This doesn't seem to be exploitable when os.name != 'nt' (Windows). The main problem is that quoting is done in distutils.py/spawn.py:_nt_quote_args and it just wraps arguments in `"`, without escaping previous existing `"`. Moreover, os.spawn in Windows uses CreateProcess underneath, which transforms the list of arguments in a single string, thus creating this flaw there. On linux, execv family functions are used and each argument is interpreted as a single filename, preventing this flaw.

Comment 8 Riccardo Schirone 2018-10-10 07:42:22 UTC

Statement:

This issue did not affect the versions of python as shipped with Red Hat Enterprise Linux 5, 6 and 7 as Linux does not use the vulnerable code.