989d921f5d
I'm very pleased to announce the release of our new website and documentation using the new toolchain with Hugo and AsciiDoctor. To get more information about the new toolchain please read the FreeBSD Documentation Project Primer[1], Hugo docs[2] and AsciiDoctor docs[3]. Acknowledgment: Benedict Reuschling <bcr@> Glen Barber <gjb@> Hiroki Sato <hrs@> Li-Wen Hsu <lwhsu@> Sean Chittenden <seanc@> The FreeBSD Foundation [1] https://docs.FreeBSD.org/en/books/fdp-primer/ [2] https://gohugo.io/documentation/ [3] https://docs.asciidoctor.org/home/ Approved by: doceng, core
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5.8 KiB
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145 lines
5.8 KiB
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-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
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FreeBSD-SA-20:13.libalias Security Advisory
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The FreeBSD Project
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Topic: Memory disclosure vulnerability in libalias
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Category: core
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Module: libalias
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Announced: 2020-05-12
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Credits: Vishnu Dev TJ working with Trend Micro Zero Day Initiative
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Affects: All supported versions of FreeBSD
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Corrected: 2020-05-12 16:52:08 UTC (stable/12, 12.1-STABLE)
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2020-05-12 16:54:39 UTC (releng/12.1, 12.1-RELEASE-p5)
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2020-05-12 16:52:08 UTC (stable/11, 11.4-STABLE)
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2020-05-12 16:54:39 UTC (releng/11.4, 11.4-BETA1-p1)
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2020-05-12 16:54:39 UTC (releng/11.3, 11.3-RELEASE-p9)
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CVE Name: CVE-2020-7455
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:https://security.FreeBSD.org/>.
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I. Background
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The ipfw(4) system facility allows IP packet filtering, redirecting, and
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traffic accounting. The ipfw(4) packet filter also contains two different
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methods of accomplishing network address translation (NAT): in-kernel and
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userspace. Both implementations use the same functions provided by libalias.
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The libalias(3) library is a collection of functions for aliasing and
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dealiasing of IP packets, intended for masquerading and NAT. Additionally,
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libalias(3) includes modules to support protocols that require additional
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logic to support address translation.
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Note: libalias(3) is not used by either the pf(4) or ipf(4) firewalls.
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II. Problem Description
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The FTP packet handler in libalias incorrectly calculates some packet
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lengths. This may result in disclosing small amounts of memory from the
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kernel (for the in-kernel NAT implementation) or from the process space for
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natd (for the userspace implementation).
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III. Impact
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A malicious attacker could send specially constructed packets that exploit the
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erroneous calculation allowing the attacker to disclose small amount of memory
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either from the kernel (for the in-kernel NAT implementation) or from the
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process space for natd (for the userspace implementation).
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IV. Workaround
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No workaround is available. Only systems using NAT and ipfw together are
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affected. Systems using ipfw without NAT, or systems leveraging pf(4) or
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ipf(4) are not affected.
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V. Solution
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Upgrade your vulnerable system to a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date,
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and reboot.
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Perform one of the following:
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1) To update your vulnerable system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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# shutdown -r +10min "Rebooting for a security update"
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2) To update your vulnerable system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch https://security.FreeBSD.org/patches/SA-20:13/libalias.patch
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# fetch https://security.FreeBSD.org/patches/SA-20:13/libalias.patch.asc
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# gpg --verify libalias.patch.asc
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b) Apply the patch. Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/12/ r360973
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releng/12.1/ r360974
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stable/11/ r360973
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releng/11.4/ r360974
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releng/11.3/ r360974
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-7455>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:13.libalias.asc>
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