Protect yourself against future threats.
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AUSCERT External Security Bulletin Redistribution
ESB-2019.0410.3
openssh security update
26 March 2019
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AusCERT Security Bulletin Summary
---------------------------------
Product: openssh
Publisher: Debian
Operating System: Debian GNU/Linux 9
Debian GNU/Linux 8
Impact/Access: Modify Arbitrary Files -- Remote with User Interaction
Provide Misleading Information -- Remote with User Interaction
Unauthorised Access -- Remote with User Interaction
Resolution: Patch/Upgrade
CVE Names: CVE-2019-6111 CVE-2019-6109 CVE-2018-20685
Reference: ESB-2019.0399
ESB-2019.0164.2
Original Bulletin:
http://www.debian.org/security/2019/dsa-4387
https://lists.debian.org/debian-security-announce/2019/msg00045.html
https://lists.debian.org/debian-lts-announce/2019/03/msg00030.html
Comment: This bulletin contains three (3) advisories.
Revision History: March 26 2019: Added DLA 1728-1
March 4 2019: update DSA-4387-2 included
February 11 2019: Initial Release
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Debian Security Advisory DSA-4387-1 security@debian.org
https://www.debian.org/security/ Yves-Alexis Perez
February 09, 2019 https://www.debian.org/security/faq
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Package : openssh
CVE ID : CVE-2018-20685 CVE-2019-6109 CVE-2019-6111
Debian Bug : 793412 919101
Harry Sintonen from F-Secure Corporation discovered multiple vulnerabilities in
OpenSSH, an implementation of the SSH protocol suite. All the vulnerabilities
are in found in the scp client implementing the SCP protocol.
CVE-2018-20685
Due to improper directory name validation, the scp client allows servers to
modify permissions of the target directory by using empty or dot directory
name.
CVE-2019-6109
Due to missing character encoding in the progress display, the object name
can be used to manipulate the client output, for example to employ ANSI
codes to hide additional files being transferred.
CVE-2019-6111
Due to scp client insufficient input validation in path names sent by
server, a malicious server can do arbitrary file overwrites in target
directory. If the recursive (-r) option is provided, the server can also
manipulate subdirectories as well.
.
The check added in this version can lead to regression if the client and
the server have differences in wildcard expansion rules. If the server is
trusted for that purpose, the check can be disabled with a new -T option to
the scp client.
For the stable distribution (stretch), these problems have been fixed in
version 1:7.4p1-10+deb9u5.
We recommend that you upgrade your openssh packages.
For the detailed security status of openssh please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/openssh
Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/
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Debian Security Advisory DSA-4387-2 security@debian.org
https://www.debian.org/security/ Yves-Alexis Perez
March 02, 2019 https://www.debian.org/security/faq
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Package : openssh
CVE ID : CVE-2019-6111
Debian Bug : 923486
It was found that a security update (DSA-4387-1) of OpenSSH, an implementation
of the SSH protocol suite, was incomplete. This update did not completely fix
CVE-2019-6111, an arbitrary file overwrite vulnerability in the scp client
implementing the SCP protocol.
For the stable distribution (stretch), this problem has been fixed in
version 1:7.4p1-10+deb9u6.
We recommend that you upgrade your openssh packages.
For the detailed security status of openssh please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/openssh
Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/
=================================================================================
Package : openssh
Version : 1:6.7p1-5+deb8u8
CVE ID : CVE-2018-20685 CVE-2019-6109 CVE-2019-6111
Debian Bug : 793412 919101 923486
Multiple scp client vulnerabilities have been discovered in OpenSSH, the
premier connectivity tool for secure remote shell login and secure file
transfer.
CVE-2018-20685
In scp.c, the scp client allowed remote SSH servers to bypass
intended access restrictions via the filename of . or an empty
filename. The impact was modifying the permissions of the target
directory on the client side.
CVE-2019-6109
Due to missing character encoding in the progress display, a
malicious server (or Man-in-The-Middle attacker) was able to employ
crafted object names to manipulate the client output, e.g., by using
ANSI control codes to hide additional files being transferred. This
affected refresh_progress_meter() in progressmeter.c.
CVE-2019-6111
Due to the scp implementation being derived from 1983 rcp, the server
chooses which files/directories are sent to the client. However, the
scp client only performed cursory validation of the object name
returned (only directory traversal attacks are prevented). A
malicious scp server (or Man-in-The-Middle attacker) was able to
overwrite arbitrary files in the scp client target directory. If
recursive operation (-r) was performed, the server was able to
manipulate subdirectories, as well (for example, to overwrite the
.ssh/authorized_keys file).
For Debian 8 "Jessie", these problems have been fixed in version
1:6.7p1-5+deb8u8.
We recommend that you upgrade your openssh packages.
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
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