openssh: CVE-2018-20685: scp.c in the scp client allows remote SSH servers to bypass intended access restrictions

Debian Bug report logs - #919101
openssh: CVE-2018-20685: scp.c in the scp client allows remote SSH servers to bypass intended access restrictions

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Salvatore Bonaccorso <carnil@debian.org>

To: Debian Bug Tracking System <submit@bugs.debian.org>

Subject: openssh: CVE-2018-20685: scp.c in the scp client allows remote SSH servers to bypass intended access restrictions

Date: Sat, 12 Jan 2019 18:02:33 +0100

Source: openssh
Version: 1:7.9p1-4
Severity: important
Tags: patch security upstream
Control: found -1 1:7.4p1-10
Control: found -1 1:7.4p1-10+deb9u4

Hi,

The following vulnerability was published for openssh.

CVE-2018-20685[0]:
| In OpenSSH 7.9, scp.c in the scp client allows remote SSH servers to
| bypass intended access restrictions via the filename of . or an empty
| filename.

More information are found in [1], where upstream fixed it in [2].
There are related issues described in [1] which I explicitly do not
track in this bug as they are yet not addressed upstream (and did not
want to mix report). They are described in [1] as issues #2, #3 and #4
and got own CVEs (CVE-2019-6109, CVE-2019-6110, CVE-2019-6111). Not
sure if upstream intends to adress those as well.

The described vulnerabilities would require that a victim accepts the
wrong host fingerpring though of a man-in-the mittle attacker server.

If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2018-20685
    https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20685
[1] https://sintonen.fi/advisories/scp-client-multiple-vulnerabilities.txt
[2] https://github.com/openssh/openssh-portable/commit/6010c0303a422a9c5fa8860c061bf7105eb7f8b2

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore

Message #12 received at 919101-submitter@bugs.debian.org (full text, mbox, reply):

From: Colin Watson <cjwatson@debian.org>

To: 919101-submitter@bugs.debian.org

Subject: Bug #919101 in openssh marked as pending

Date: Sat, 12 Jan 2019 18:50:05 +0000

Control: tag -1 pending

Hello,

Bug #919101 in openssh reported by you has been fixed in the
Git repository and is awaiting an upload. You can see the commit
message below and you can check the diff of the fix at:

https://salsa.debian.org/ssh-team/openssh/commit/7e34cc252e1c42369aaaa8e1c379699ccf8c9e0e

------------------------------------------------------------------------
scp: disallow empty incoming filename or "."

Closes: #919101
------------------------------------------------------------------------

(this message was generated automatically)
-- 
Greetings

https://bugs.debian.org/919101

Message #19 received at 919101-close@bugs.debian.org (full text, mbox, reply):

From: Colin Watson <cjwatson@debian.org>

To: 919101-close@bugs.debian.org

Subject: Bug#919101: fixed in openssh 1:7.9p1-5

Date: Sun, 13 Jan 2019 11:34:35 +0000

Source: openssh
Source-Version: 1:7.9p1-5

We believe that the bug you reported is fixed in the latest version of
openssh, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 919101@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Colin Watson <cjwatson@debian.org> (supplier of updated openssh package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


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Hash: SHA256

Format: 1.8
Date: Sun, 13 Jan 2019 11:22:45 +0000
Source: openssh
Binary: openssh-client openssh-server openssh-sftp-server openssh-tests ssh ssh-askpass-gnome openssh-client-udeb openssh-server-udeb
Architecture: source
Version: 1:7.9p1-5
Distribution: unstable
Urgency: high
Maintainer: Debian OpenSSH Maintainers <debian-ssh@lists.debian.org>
Changed-By: Colin Watson <cjwatson@debian.org>
Description:
 openssh-client - secure shell (SSH) client, for secure access to remote machines
 openssh-client-udeb - secure shell client for the Debian installer (udeb)
 openssh-server - secure shell (SSH) server, for secure access from remote machines
 openssh-server-udeb - secure shell server for the Debian installer (udeb)
 openssh-sftp-server - secure shell (SSH) sftp server module, for SFTP access from remot
 openssh-tests - OpenSSH regression tests
 ssh        - secure shell client and server (metapackage)
 ssh-askpass-gnome - interactive X program to prompt users for a passphrase for ssh-ad
Closes: 858050 917342 919101
Changes:
 openssh (1:7.9p1-5) unstable; urgency=high
 .
   * Move /etc/ssh/moduli to openssh-server, since it's reasonably large and
     only used by sshd (closes: #858050).
   * Drop obsolete alternate build-dependency on libssl1.0-dev (closes:
     #917342).
   * CVE-2018-20685: Apply upstream scp patch to disallow empty incoming
     filename or ones that refer to the current directory (closes: #919101).
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Message #24 received at 919101-close@bugs.debian.org (full text, mbox, reply):

From: Yves-Alexis Perez <corsac@debian.org>

To: 919101-close@bugs.debian.org

Subject: Bug#919101: fixed in openssh 1:7.4p1-10+deb9u5

Date: Sat, 09 Feb 2019 21:47:35 +0000

Source: openssh
Source-Version: 1:7.4p1-10+deb9u5

We believe that the bug you reported is fixed in the latest version of
openssh, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 919101@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Yves-Alexis Perez <corsac@debian.org> (supplier of updated openssh package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Format: 1.8
Date: Fri, 08 Feb 2019 15:25:55 +0100
Source: openssh
Binary: openssh-client openssh-client-ssh4 openssh-server openssh-sftp-server ssh ssh-krb5 ssh-askpass-gnome openssh-client-udeb openssh-server-udeb
Architecture: source
Version: 1:7.4p1-10+deb9u5
Distribution: stretch-security
Urgency: high
Maintainer: Debian OpenSSH Maintainers <debian-ssh@lists.debian.org>
Changed-By: Yves-Alexis Perez <corsac@debian.org>
Description:
 openssh-client - secure shell (SSH) client, for secure access to remote machines
 openssh-client-ssh4 - secure shell (SSH) client for legacy SSH1 protocol
 openssh-client-udeb - secure shell client for the Debian installer (udeb)
 openssh-server - secure shell (SSH) server, for secure access from remote machines
 openssh-server-udeb - secure shell server for the Debian installer (udeb)
 openssh-sftp-server - secure shell (SSH) sftp server module, for SFTP access from remot
 ssh        - secure shell client and server (metapackage)
 ssh-askpass-gnome - interactive X program to prompt users for a passphrase for ssh-ad
 ssh-krb5   - secure shell client and server (transitional package)
Closes: 793412 919101
Changes:
 openssh (1:7.4p1-10+deb9u5) stretch; urgency=high
 .
   * Non-maintainer upload by the Security Team.
   * CVE-2018-20685: disallow empty filenames or ones that refer to the current
     directory (Closes: #919101)
   * CVE-2019-6109: sanitize scp filenames via snmprintf (Closes: #793412)
   * CVE-2019-6111: check in scp client that filenames sent during
     remote->local directory copies satisfy the wildcards specified by the user
Checksums-Sha1:
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