Bug 1506630 – CVE-2017-15906 openssh: Improper write operations in readonly mode allow for zero-length file creation

Bugzilla will be upgraded to version 5.0. The upgrade date is tentatively scheduled for 2 December 2018, pending final testing and feedback.

Bug 1506630 - (CVE-2017-15906) CVE-2017-15906 openssh: Improper write operations in readonly mode allow for zero-length file creation

Summary:	CVE-2017-15906 openssh: Improper write operations in readonly mode allow for ...

Status:	NEW

Aliases:	CVE-2017-15906

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	low Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=low,public=20171003,reported=2...
Keywords:	Security

Depends On:	1506631 1517226
Blocks:	1498774 1506633
	Show dependency tree / graph

Reported:	2017-10-26 09:16 EDT by Andrej Nemec
Modified:	2018-04-10 04:37 EDT (History)
CC List:	14 users (show)

See Also:
Fixed In Version:	openssh 7.6
Doc Type:	If docs needed, set a value
Doc Text:
Story Points:	---
Clone Of:
Environment:
Last Closed:
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2018:0980	None	None	None	2018-04-10 04:37 EDT

Groups: None (edit)

Description Andrej Nemec 2017-10-26 09:16:17 EDT

The process_open function in sftp-server.c in OpenSSH before 7.6 does not properly prevent write operations in readonly mode, which allows attackers to create zero-length files.

Upstream patch:

https://github.com/openbsd/src/commit/a6981567e8e215acc1ef690c8dbb30f2d9b00a19

References:

https://www.openssh.com/txt/release-7.6

Comment 1 Andrej Nemec 2017-10-26 09:16:50 EDT

Created openssh tracking bugs for this issue:

Affects: fedora-all [bug 1506631]

Comment 2 Huzaifa S. Sidhpurwala 2017-11-01 01:45:56 EDT

Analysis:

It seems the maximum impact of this flaw is that the attacker can create an extremely large number of zero length files to fill up a harddisk on a remote server which the attacker has read-only access to.

Comment 10 errata-xmlrpc 2018-04-10 04:37:25 EDT

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:0980 https://access.redhat.com/errata/RHSA-2018:0980

Note You need to log in before you can comment on or make changes to this bug.