📖 ~4 min read • Source: FreeBSD VuXML
VuXML topic: Use-After-Free Vulnerability in pcsc-lite
Related CVEs: CVE-2016-10109
Upstream summary: Peter Wu on Openwall mailing-list reports: The issue allows a local attacker to cause a Denial of Service, but can potentially result in Privilege Escalation since the daemon is running as root. while any local user can connect to the Unix socket. Fixed by patch which is released with hpcsc-lite 1.8.20.
Table of contents
Symptom & Impact
pcsc-lite runs as a long-lived process on FreeBSD 15, 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. pcsc-lite is a genuine long-running service, so restart steps do apply — but confirm the service name first with service -e | grep pcsc-lite, since it often differs from the package name (bind ships named).
Environment & Reproduction
Reproduction targets FreeBSD 15. Confirm with freebsd-version -kru, uname -a, and the installed package via pkg info pcsc-lite and pkg query "%n-%v" pcsc-lite. Capture system state with pkg audit -F and service -e. Trigger the workflow that exposes pcsc-lite while collecting tail -200 /var/log/messages, dmesg -a, and /var/log/pkg.log.
Root Cause Analysis
Root cause is tracked at FreeBSD VuXML. The FreeBSD ports security team shipped a corrective pcsc-lite port revision; hosts on an outdated build remain exposed. Correlate /var/log/pkg.log with /var/log/messages and kernel state in sysctl kern.lastpid + sysctl kern.osreldate to isolate the change that triggered the failure mode.
Quick Triage
Quick triage: service pcscd status, tail -100 /var/log/messages, pkg audit -F, pkg version -v pcsc-lite, and pfctl -sr (or ipfw list) to confirm firewall posture. For kernel issues: dmesg -a | tail -100 and kldstat.
Step-by-Step Diagnosis
1) service -e to enumerate failed services. 2) tail -F /var/log/messages and dmesg. 3) Validate firewall via pfctl -sr -v or ipfw show. 4) pkg check -B pcsc-lite for integrity. 5) pkg install -fy pcsc-lite to reinstall if tampered. 6) Correlate findings with /var/log/pkg.log and FreeBSD VuXML to pin the commit that introduced the regression.
Solution – Primary Fix
Primary fix: install the corrective pcsc-lite port revision referenced by FreeBSD VuXML. Typical commands: sudo pkg update, sudo pkg upgrade pcsc-lite (or sudo pkg upgrade -y for the whole system), then sudo service pcscd restart, and pkg audit to confirm no remaining advisories. For ports tree builders: sudo portsnap fetch update + cd /usr/ports/<cat>/pcsc-lite && sudo make deinstall reinstall clean. Reboot if the kernel module is involved.
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Solution – Alternative Approaches
Alternatives include locking the package with sudo pkg lock pcsc-lite until vetted, downgrading via pkg install <older-version> from a pinned repo, switching the FreeBSD pkg repository between quarterly and latest in /usr/local/etc/pkg/repos/FreeBSD.conf, isolating the affected service in a jail (iocage/bastille) with stricter firewall rules, or replacing the service with a vendored static build for the period between exposure detection and full rollout.
Verification & Acceptance Criteria
Acceptance: pkg info pcsc-lite shows the expected fixed version, service pcscd status is running, pkg audit returns no advisory for pcsc-lite, tail -50 /var/log/messages shows no errors after restart, and the original reproduction for pcsc-lite no longer triggers across two consecutive runs.
Rollback Plan
Capture state with pkg query "%n-%v" > /root/pkg-pre.txt and a ZFS boot-environment snapshot: bectl create pre-pcsc-lite-patch. To revert, run sudo pkg install -f <previous-version> or boot the previous BE via bectl activate pre-pcsc-lite-patch && reboot. For kernel/loader changes, drop to the loader prompt and select the previous boot environment.
Prevention & Hardening
Prevent recurrence by scheduling pkg audit -F via periodic.conf (daily_status_security_pkgaudit_enable="YES"), subscribing to freebsd-security-notifications, mirroring through a local pkg repo managed by poudriere, version-pinning sensitive packages with pkg lock, enabling automatic ZFS BE snapshots before upgrades, and monitoring file integrity via mtree or aide. Apply the CIS FreeBSD hardening checklist where applicable and harden jails with allow.* tunables in /etc/jail.conf.
Related Errors & Cross-Refs
Related issues that commonly surface alongside pcsc-lite: pkg lock contention, mismatched ABI after kernel/userland skew (freebsd-version vs uname -K), pf rule drift, and stale shared-library references after upgrade (pkg check -d).
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References & Further Reading
Primary reference: FreeBSD VuXML. Supporting docs: FreeBSD Handbook, man pkg, man freebsd-update, man pfctl, man ipfw, man bectl, man periodic.conf, the FreeBSD Security Advisories at security.freebsd.org, and /usr/ports/UPDATING for port-specific notes implicated in this advisory.
