Bug 1524485 (CVE-2017-17087)

Summary:	CVE-2017-17087 vim: Sets the group ownership of a .swp file to the editor's primary group
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	gchamoul, karsten, zdohnal
Target Milestone:	---	Keywords:	Reopened, Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	vim 8.0.1263	Doc Type:	If docs needed, set a value
Doc Text:	It was found that the swap file created by vim when opening a file was using the user's primary group instead of the file's group. An attacker belonging to the victim's primary group could use this flaw to read the vim swap file.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-01-02 17:36:33 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:	1524489
Bug Blocks:	1508790

Description Andrej Nemec 2017-12-11 15:33:58 UTC

fileio.c in Vim prior to 8.0.1263 sets the group ownership of a .swp file to the editor's primary group (which may be different from the group ownership of the original file), which allows local users to obtain sensitive information by leveraging an applicable group membership, as demonstrated by /etc/shadow owned by root:shadow mode 0640, but /etc/.shadow.swp owned by root:users mode 0640, a different vulnerability than CVE-2017-1000382.

References:

http://openwall.com/lists/oss-security/2017/11/27/2
https://groups.google.com/forum/#!msg/vim_dev/sRT9BtjLWMk/BRtSXNU4BwAJ

Upstream patch:

https://github.com/vim/vim/commit/5a73e0ca54c77e067c3b12ea6f35e3e8681e8cf8

Comment 1 Andrej Nemec 2017-12-11 15:35:17 UTC

Created vim tracking bugs for this issue:

Affects: fedora-26 [bug 1524489]

Comment 4 Cedric Buissart 2018-01-02 17:31:04 UTC

In Red Hat Enterprise Linux, the default primary group is unique to the user (e.g.: root's primary group is root, user1's primary group will be user1, etc.).
Thus unless default primary group is modified at creation time, or at execution time (e.g. via newgrp or sg), this vulnerability will not be effective.

Comment 5 Cedric Buissart 2018-01-02 17:32:08 UTC

Statement:

Red Hat Product Security has rated this issue as having Low security impact. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.