*** This bug is a security vulnerability *** Public security bug reported:
Apparently mDNS can be used for ddos amplification, see for instance https://mdns.shadowserver.org/ and https://www.us-cert.gov/ncas/alerts/TA14-017A Steps to reproduce: dig @rusk.hpc2n.umu.se -p 5353 -t ptr _services._dns-sd._udp.local The response is supposedly 2-10 times the size of the query, making for a moderate but noticeable amplification. Workarounds are easy, but not responding outside localnet by default is probably reasonable for mDNS. Reproduced at at least trusty and precise, would be very surprised if it didn't also apply to xenial but I left my xenial laptop at home today. :) ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: avahi-daemon 0.6.30-5ubuntu2.1 ProcVersionSignature: Ubuntu 3.13.0-83.127~precise1-generic 3.13.11-ckt35 Uname: Linux 3.13.0-83-generic x86_64 NonfreeKernelModules: openafs ApportVersion: 2.0.1-0ubuntu17.13 Architecture: amd64 Date: Fri Apr 15 12:12:22 2016 MarkForUpload: True ProcEnviron: LANGUAGE=en_US:en TERM=xterm PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: avahi UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: avahi (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug precise trusty ** Information type changed from Private Security to Public Security -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1570788 Title: Makes mDNS ddos amplification attack possible To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1570788/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
