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 ...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2017-15906
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1506631 1517226
Blocks: 1498774 1506633
TreeView+ depends on / blocked
 
Reported: 2017-10-26 13:16 UTC by Andrej Nemec
Modified: 2021-06-10 13:22 UTC (History)
14 users (show)

Fixed In Version: openssh 7.6
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Clone Of:
Environment:
Last Closed: 2019-06-08 03:30:04 UTC
Embargoed:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2018:0980 0 None None None 2018-04-10 08:37:35 UTC

Description Andrej Nemec 2017-10-26 13:16:17 UTC 
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 13:16:50 UTC 
Created openssh tracking bugs for this issue:

Affects: fedora-all [bug 1506631]
Comment 2 Huzaifa S. Sidhpurwala 2017-11-01 05:45:56 UTC 
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 08:37:25 UTC 
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
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