21 April, 2020 by security-advisories@freebsd.org | freebsd
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FreeBSD-SA-20:11.openssl Security Advisory
The FreeBSD Project
Topic: OpenSSL remote denial of service vulnerability
Category: contrib
Module: openssl
Announced: 2020-04-21
Credits: Bernd Edlinger
Affects: FreeBSD 12.1
Corrected: 2020-04-21 15:47:58 UTC (stable/12, 12.1-STABLE)
2020-04-21 15:53:08 UTC (releng/12.1, 12.1-RELEASE-p4)
CVE Name: CVE-2020-1967
For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:https://security.FreeBSD.org/>.
I. Background
FreeBSD includes software from the OpenSSL Project. The OpenSSL Project is a
collaborative effort to develop a robust, commercial-grade, full-featured
Open Source toolkit for the Transport Layer Security (TLS) and Secure Sockets
Layer (SSL) protocols. It is also a full-strength general purpose
cryptography library.
II. Problem Description
Server or client applications that call the SSL_check_chain() function during
or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a
result of incorrect handling of the "signature_algorithms_cert" TLS
extension. The crash occurs if an invalid or unrecognized signature
algorithm is received from the peer.
III. Impact
A malicious peer could exploit the NULL pointer dereference crash, causing a
denial of service attack.
IV. Workaround
No workaround is available.
V. Solution
Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.
Perform one of the following:
1) 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
# shutdown -r +10min "Rebooting for a security update"
2) 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.
# fetch https://security.FreeBSD.org/patches/SA-20:11/openssl.patch
# fetch https://security.FreeBSD.org/patches/SA-20:11/openssl.patch.asc
# gpg --verify openssl.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
Restart all daemons that use the library, or reboot the system.
VI. Correction details
The following list contains the correction revision numbers for each
affected branch.
Branch/path Revision
- -------------------------------------------------------------------------
stable/12/ r360147
releng/12.1/ r360150
- -------------------------------------------------------------------------
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://svn.freebsd.org/base
Or visit the following URL, replacing NNNNNN with the revision number:
<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
VII. References
<URL:https://www.openssl.org/news/secadv/20200421.txt>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-1967>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:11.openssl.asc>
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------------------------------------------------------------------
OpenSSL Security Advisory [21 April 2020]
https://www.openssl.org/news/secadv/20200421.txt
=========================================
Segmentation fault in SSL_check_chain (CVE-2020-1967)
=====================================================
Severity: High
Server or client applications that call the SSL_check_chain() function during or
after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a
result of incorrect handling of the "signature_algorithms_cert" TLS extension.
The crash occurs if an invalid or unrecognised signature algorithm is received
from the peer. This could be exploited by a malicious peer in a Denial of
Service attack.
OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This
issue did not affect OpenSSL versions prior to 1.1.1d.
Affected OpenSSL 1.1.1 users should upgrade to 1.1.1g
This issue was found by Bernd Edlinger and reported to OpenSSL on 7th April
2020. It was found using the new static analysis pass being implemented in GCC,
-fanalyzer. Additional analysis was performed by Matt Caswell and Benjamin
Kaduk.
Note
=====
This issue did not affect OpenSSL 1.0.2 however these versions are out of
support and no longer receiving public updates. Extended support is available
for premium support customers: https://www.openssl.org/support/contracts.html
This issue did not affect OpenSSL 1.1.0 however these versions are out of
support and no longer receiving updates.
Users of these versions should upgrade to OpenSSL 1.1.1.
References
==========
URL for this Security Advisory:
https://www.openssl.org/news/secadv/20200421.txt
Note: the online version of the advisory may be updated with additional details
over time.
For details of OpenSSL severity classifications please see:
https://www.openssl.org/policies/secpolicy.html
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| CVE-ID |
|---|
CVE-2020-1967
|
• CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
|
| Description |
|---|
| Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f). |
| References |
|---|
| Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete. |
|
|
| Assigning CNA |
|---|
| OpenSSL Software Foundation |
| Date Entry Created |
|---|
| 20191203 | Disclaimer: The entry creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE. |
| Phase (Legacy) |
|---|
| Assigned (20191203) |
| Votes (Legacy) |
|---|
|
| Comments (Legacy) |
|---|
|
|
| Proposed (Legacy) |
|---|
| N/A |
| This is an entry on the CVE List, which provides common identifiers for publicly known cybersecurity vulnerabilities. |
|
|
| For More Information: CVE Request Web Form (select “Other” from dropdown) |
