during our BlackHat US 2014 talk titled “Evasion of High-End IPS Devices in the Age of IPv6”, among others we discussed a Snort preprocessor rule (116:456) which, when enabled (not the case by default), triggers an alert when an IPv6 datagram with nine (9) or more IPv6 Extension Headers is used (such a header was used by us to evade Snort). However, we mentioned that:
RA Guard Evasion is well-known in the IPv6 “circles”; there is RFC 7113 Advice for IPv6 Router Advertisement Guard (RA-Guard) and many interesting blog-posts like this one here, here, and this excellent write-up here that discuss this issue.
Moreover, as Jim Smalls states in his comprehensive “IPv6 Attacks and Countermeasures” presentation given at the North American IPv6 Summit 2013, DHCPv6 Guard or a corresponding IPv6 ACL can stop a DHCPv6 Rogue Servers, but (only?) for non-malicious/non-fragmented DHCPv6 packets (slide 35). However, at that time there wasn’t any known attack tool in the wild that had the fragmentation evasion built in.
Most of you are probably aware of the recently discovered/-closed severe ntpd vulnerabilities (CVE-2014-9293, CVE-2014-9294, CVE-2014-9295, CVE-2014-9296, see also the initial ntp.org security notice). Some days ago the Project Zero team at Google published a blog post “Finding and exploiting ntpd vulnerabilities” with additional details. In this one they mentioned a seemingly minor but quite important detail: on a default OS X installation one of the built-in protection mechanisms of ntpd (that is the restriction to process certain packets only if they are sourced on the local machine) can easily be circumvented by sending IPv6 packets with a spoofed source address of ::1 (the equivalent to 127.0.0.1 in IPv4 which would be discarded by the kernel once received from an external source).
This brought up a number of more generic questions:
a) Should such packets having as source address the IPv6 loopback one be processed at all?
b) Which OSs process such packets?
c) How can we protect our systems from them?
As we promised some days ago here’s the fourth round of Troopers15 talks (the first three can be found here). We really can’t wait for the con ourselves 😉 !
After we recently released the “Linux IPv6 Hardening Guide” we got a number of suggestions “could you pls provide a similar document for $OS?” (btw: thanks to you all for the overwhelming interest in the Linux document and the active discussion of ip6tables rule approaches on the ipv6hackers mailing list).
We were recently approached by a customer asking us for support along the lines of “do you have any recommendations as for strict hardening of IPv6 parameters on Linux systems?”. It turned out that the systems in question process quite sensitive data and are located in certain, not too big network segments with very high security requirements.
We just released a white paper authored by Antonios Atlasis that provides an overview which pentesting tools currently support IPv6 and how to (still) use them if that’s not the case. It can be found in our newsletter section.