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Category:   Application (File Transfer/Sharing)  >   FTP (Generic) Vendors:   FreeBSD
(FreeBSD Issues Fix) BSD FTP Client HTTP Redirect Flaw Lets Remote Servers Execute Arbitrary Commands on the Target User's System
SecurityTracker Alert ID:  1031170
SecurityTracker URL:
CVE Reference:   CVE-2014-8517   (Links to External Site)
Date:  Nov 5 2014
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  Exploit Included:  Yes  

Description:   A vulnerability was reported in some BSD-based FTP clients. A remote user can cause arbitrary commands to be executed on the target user's system.

A remote FTP server can return a specially crafted HTTP redirect to a connected client to cause the target client to execute arbitrary commands on the target system.

The vulnerability can be triggered in response to an FTP command for an HTTP resource when '-o' (output file) is not specified.

NetBSD tnftp(1) is affected. In NetBSD, the vulnerability resides in 'src/usr.bin/ftp/fetch.c'.

Apple OS X is affected.

FreeBSD is affected.

OpenBSD is not affected.

Other BSD-based systems may be affected.

Jared Mcneill reported this vulnerability.

Impact:   A remote user can cause arbitrary commands to be executed on the target connected user's system.
Solution:   FreeBSD has issued a fix.

The FreeBSD advisory is available at:

Cause:   Access control error
Underlying OS:  UNIX (FreeBSD)
Underlying OS Comments:  8.4, 9.1, 9.2, 9.3, 10.0, 10.1

Message History:   This archive entry is a follow-up to the message listed below.
Oct 30 2014 BSD FTP Client HTTP Redirect Flaw Lets Remote Servers Execute Arbitrary Commands on the Target User's System

 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-14:26.ftp

Hash: SHA512

FreeBSD-SA-14:26.ftp                                        Security Advisory
                                                          The FreeBSD Project

Topic:          Remote command execution in ftp(1)

Category:       core
Module:         ftp
Announced:      2014-11-04
Credits:        Jared McNeill, Alistair Crooks
Affects:        All supported versions of FreeBSD.
Corrected:      2014-11-04 23:29:57 UTC (stable/10, 10.1-PRERELEASE)
                2014-11-04 23:34:46 UTC (releng/10.1, 10.1-RC4-p1)
                2014-11-04 23:34:46 UTC (releng/10.1, 10.1-RC3-p1)
                2014-11-04 23:34:46 UTC (releng/10.1, 10.1-RC2-p3)
                2014-11-04 23:31:17 UTC (releng/10.0, 10.0-RELEASE-p12)
                2014-11-04 23:30:47 UTC (stable/9, 9.3-STABLE)
                2014-11-04 23:33:46 UTC (releng/9.3, 9.3-RELEASE-p5)
                2014-11-04 23:33:17 UTC (releng/9.2, 9.2-RELEASE-p15)
                2014-11-04 23:32:45 UTC (releng/9.1, 9.1-RELEASE-p22)
                2014-11-04 23:30:23 UTC (stable/8, 8.4-STABLE)
                2014-11-04 23:32:15 UTC (releng/8.4, 8.4-RELEASE-p19)
CVE Name:       CVE-2014-8517

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:>.

I.   Background

The ftp(1) userland utility is an interactive FTP client.  It can also
be used non-interactively, by providing a URL on the command line.  In
this mode, it supports HTTP in addition to FTP.

II.  Problem Description

A malicious HTTP server could cause ftp(1) to execute arbitrary

III. Impact

When operating on HTTP URIs, the ftp(1) client follows HTTP redirects,
and uses the part of the path after the last '/' from the last
resource it accesses as the output filename if '-o' is not specified.

If the output file name provided by the server begins with a pipe
('|'), the output is passed to popen(3), which might be used to
execute arbitrary commands on the ftp(1) client machine.

IV.  Workaround

No workaround is available.  Users are encouraged to replace ftp(1) in
non-interactive use by either fetch(1) or a third-party client such as
curl or wget.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.

2) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 8]
# fetch
# fetch
# gpg --verify ftp-8.patch.asc

[All other versions]
# fetch
# fetch
# gpg --verify ftp.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile ftp.  Execute the following commands as root:

# cd /usr/src/usr.bin/ftp
# make && make install

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                         r274108
releng/8.4/                                                       r274111
stable/9/                                                         r274109
releng/9.1/                                                       r274112
releng/9.2/                                                       r274113
releng/9.3/                                                       r274114
stable/10/                                                        r274107
releng/10.0/                                                      r274110
releng/10.1/                                                      r274115
- -------------------------------------------------------------------------

To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:

# svn diff -cNNNNNN --summarize svn://

Or visit the following URL, replacing NNNNNN with the revision number:


VII. References


The latest revision of this advisory is available at

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