FreeBSD 12 — ntp — multiple vulnerabilities (20 CVEs) — patch and remediation guide

📖 ~4 min read  •  Source: FreeBSD VuXML

VuXML topic: ntp — Multiple vulnerabilities

Related CVEs: CVE-2009-0159 CVE-2009-1252 CVE-2013-5211 CVE-2014-9293 CVE-2014-9294 CVE-2014-9295 CVE-2014-9296 CVE-2015-1798  +12 more

Upstream summary: nwtime.org reports: Three ntp vulnerabilities, Depending on configuration, may have little impact up to termination of the ntpd process. NTP Bug 3610: Process_control() should exit earlier on short packets. On systems that override the default and enable ntpdc (mode 7) fuzz testing detected that a short packet will cause ntpd to read uninitialized data. NTP Bug 3596: An unauthenticated unmonitored ntpd is vulnerable to attack on IPv4 with highly predictable transmit timestamp

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

ntp runs as a long-lived process on FreeBSD 12, started at boot and holding open sockets (visible in ss -lntp), so a flaw in it stays reachable for as long as the service is up. Exploitation usually means code execution in the daemon’s own security context, memory disclosure from a process holding credentials and cached client data, or a crash that takes the listener down. Workers started before the upgrade keep running the old binary until the service is restarted. ntp is a genuine long-running service, so restart steps do apply — but confirm the service name first with service -e | grep ntp, since it often differs from the package name (bind ships named).

Environment & Reproduction

Reproduction targets FreeBSD 12. Confirm release, installed package, and capture baseline state:

freebsd-version -kru
uname -a
pkg info ntp
pkg query "%n-%v" ntp
pkg audit -F
service -e

Exercise the workload that uses ntp while collecting:

tail -200 /var/log/messages
dmesg -a | tail -200
tail -200 /var/log/pkg.log

Root Cause Analysis

Root cause is tracked at FreeBSD VuXML. The FreeBSD ports security team shipped a corrective ntp port revision; hosts on an outdated build remain exposed. Correlate package logs with system logs and kernel state to isolate the change that triggered the failure mode:

tail -500 /var/log/pkg.log
tail -500 /var/log/messages
sysctl kern.lastpid
sysctl kern.osreldate     # numeric __FreeBSD_version, e.g. 1400097

Quick Triage

Run these checks on FreeBSD 12 to confirm the failure mode and current state of ntp:

pkg version -v ntp                # installed vs available version
pkg audit ntp                     # advisory match for this package
tail -100 /var/log/messages
dmesg -a | tail -100
kldstat                              # kernel module state (for kernel/driver pkgs)
pfctl -sr 2>/dev/null || ipfw list   # only if pf/ipfw is enabled
# ntp runs as the "ntpd" service - restart it once the upgrade is in place:
# e.g. bind918→named, php83→php-fpm), check it:
service -e | grep -i ntp && service ntpd status

Step-by-Step Diagnosis

1. List enabled services (only relevant if the package provides one).

   service -e

2. Follow live logs.

   tail -F /var/log/messages
   dmesg

3. Validate firewall rules (skip if neither pf nor ipfw is enabled).

   pfctl -sr -v 2>/dev/null || ipfw show

4. Check package integrity for ntp.

   pkg check -B ntp
   pkg check -d ntp    # verify shared-library deps

5. Reinstall ntp if integrity check fails.

   pkg install -fy ntp

6. Correlate findings with /var/log/pkg.log and FreeBSD VuXML to pin the commit that introduced the regression.

Solution – Primary Fix

Install the corrective ntp port revision referenced by FreeBSD VuXML:

sudo pkg update
sudo pkg upgrade ntp              # or: sudo pkg upgrade -y for the whole system
# ntp runs as the "ntpd" service - restart it once the upgrade is in place:
sudo service ntpd restart
pkg audit ntp                    # confirm no remaining advisory for this package

For ports-tree builders (FreeBSD 13.x and earlier used portsnap; on FreeBSD 14+ the ports tree is fetched with Git):

# FreeBSD 14+ (portsnap was removed):
sudo pkg install -y git-lite
sudo git clone --depth 1 https://git.FreeBSD.org/ports.git /usr/ports
# FreeBSD 13.x and earlier:
# sudo portsnap fetch update
cd /usr/ports/<category>/ntp
sudo make deinstall reinstall clean

Reboot only if the package ships a kernel module or replaces a shared library used by long-running daemons.

Solution – Alternative Approaches

If the primary fix is not viable, choose from these alternatives:

• Lock the package until the fix is vetted:

  sudo pkg lock ntp

• Downgrade to a known-good revision. pkg install pkgname-VERSION is not a real downgrade syntax — fetch a specific build instead:

  # 1. Discover available versions across configured repos:
  pkg search -e ntp
  pkg rquery -r FreeBSD-quarterly '%n-%v' ntp
  # 2. Install from a specific saved .pkg file:
  sudo pkg add -f /path/to/ntp-<older-version>.pkg
  # 3. Or switch the host repo to the quarterly branch (see snippet below) and:
  sudo pkg upgrade -fr FreeBSD-quarterly ntp

• Switch the pkg repository between quarterly and latest by editing /usr/local/etc/pkg/repos/FreeBSD.conf:

  FreeBSD: {
    url: "pkg+https://pkg.FreeBSD.org/${ABI}/quarterly",
    mirror_type: "srv",
    signature_type: "fingerprints",
    fingerprints: "/usr/share/keys/pkg",
    enabled: yes
  }

• Isolate the affected service in a jail with stricter firewall rules:

  iocage create -n ntp-jail -r 12.4-RELEASE
  iocage set allow_raw_sockets=0 ntp-jail
  # or with Bastille:
  bastille create ntp-jail 12.4-RELEASE 10.0.0.10

• Replace the service with a vendored static build for the period between exposure detection and full rollout.

Verification & Acceptance Criteria

All of these should pass after the fix:

pkg info ntp                # shows the expected fixed version
pkg audit ntp               # no advisory for this package (exit code 0)
tail -50 /var/log/messages   # no new errors after upgrade
# If ntp ships a service, confirm it is running under its rc.d name:
# service ntpd status

The conditions described in the advisory must no longer be reported for ntp across two consecutive runs.

Rollback Plan

Capture state before any change (only ZFS root has boot environments — UFS hosts skip bectl):

pkg query "%n-%v" > /root/pkg-pre.txt
# ZFS-on-root only:
sudo bectl create pre-ntp-patch

To revert if the upgrade is bad, reinstall the previously saved .pkg file:

sudo pkg add -f /var/cache/pkg/ntp-<previous-version>.pkg
# Or activate the pre-patch boot environment and reboot (ZFS-on-root only):
sudo bectl activate pre-ntp-patch
sudo shutdown -r now

For kernel/loader changes on a UFS host, boot the previous kernel from the loader prompt (press 3 at the menu, then boot kernel.old).

Prevention & Hardening

Prevent recurrence on FreeBSD 12 hosts running ntp:

• Enable the daily security pkg audit in /etc/periodic.conf:

  daily_status_security_pkgaudit_enable="YES"

• Subscribe to freebsd-security-notifications at lists.freebsd.org.

• Mirror through a local pkg repository managed by poudriere:

  poudriere jail -c -j 12amd64 -v 12.4-RELEASE
  poudriere ports -c -p default
  poudriere bulk -j 12amd64 -p default <category>/ntp

• Version-pin sensitive packages:

  sudo pkg lock ntp

• Take an automatic ZFS boot-environment snapshot before every upgrade (ZFS root only):

  sudo bectl create pre-upgrade-$(date +%Y%m%d)

• Monitor file integrity (create a baseline, verify against it later):

  # Create a baseline (use -c; target /usr/local/etc, /etc, /boot — NOT /):
  sudo mtree -c -K sha256digest -p /usr/local/etc > /var/db/usr-local-etc.mtree
  sudo mtree -c -K sha256digest -p /etc          > /var/db/etc.mtree
  # Verify later:
  sudo mtree -p /usr/local/etc < /var/db/usr-local-etc.mtree
  # Or with AIDE for a richer ruleset:
  sudo pkg install -y aide && sudo aide --init && sudo aide --check

• Harden jails with allow.* tunables in /etc/jail.conf:

  ntp_jail {
    allow.raw_sockets = 0;
    allow.sysvipc    = 0;
    allow.mount      = 0;
    allow.chflags    = 0;
  }

Related Errors & Cross-Refs

Issues that commonly surface alongside a ntp update: pkg lock contention, mismatched ABI after kernel/userland skew, pf rule drift, and stale shared-library references after upgrade. Triage with:

freebsd-version -kru
uname -K
pkg check -d
pfctl -sr

View all freebsd-12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Primary reference: FreeBSD VuXML. Useful manual pages on FreeBSD 12:

man pkg
man freebsd-update
man pfctl
man ipfw
man bectl
man periodic.conf

Other resources: the FreeBSD Handbook, the FreeBSD Security Advisories at security.freebsd.org, and the /usr/ports/UPDATING file for port-specific notes implicated in this advisory.