Bold Statements
Hi,
MS just released a new guide on securing Active Directory. At the first glance seems a fairly comprehensive document to me.
At this occasion I may furthermore draw your attention to our (German language) newsletter no. 40 covering hardening MS Windows Server 2008 + AD.
have a good one,
Enno
Continue readingRecently Jozef Pivarník and Matěj Grégr published an excellent write-up on RA Guard & evasion techniques. Amongst others they tested the “undetermined-transport” ACL we described here and here. As it turns out the “workaround” for implementing undetermined-transport on platforms seemingly not supporting it, causes some bad collateral damage: the respective port does not forward any IPv6 packets any more (this was brought to my attention by Roberto Taccon). We had done some tests after applying it (by means of the “workaround”) but we had just looked at fragmented RA packets (which did not get through => test succeeded). So, frankly: the undetermined-transport trick does not make sense at all on the “unsupported platforms”…
Jim Small didn’t notice this either, in his great presentation at the North American IPv6 Summit (which, btw, to the best of our knowledge is the best overview of ACL approaches to counter common IPv6 attacks on the local link).
Furthermore it should be noted that Jozef and Matej describe some really interesting ways to evade current implementations, incl. an evasion variant merely based on extension headers (without fragmentation) that we hadn’t been aware of before. These will be included in these workshops.
Obviously much more research (and vendor scrutiny) is needed as for RA Guard…
have a great week everybody
Enno
Continue readingDue to “popular demand” and given Marc couldn’t join us at the IPv6 Security Summit (as flights into FRA were canceled that day due to snow) we decided to invite him and Antonios Atlasis another time, to present their knowledge, skills & voodoo in two workshops held in Heidelberg, in late June. More details can be found here.
See you all potentially at the Heise IPv6 Kongress, take care
Enno
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Hi,
on the [ipv6-ops] mailing list currently there’s some discussion about RA guard support on switches from different vendors.
Stefan, one of our students (btw: working on a topic similar to this session), quickly put together a preliminary list, based on publicly available information (read: the WWW ;-)). Some of you may find this useful; it can be found here. Furthermore on the list this link was mentioned which seems to provide some info as well (albeit potentially not very up-to-date).
If anyone of you has better/more information pls feel free to share by leaving a comment. The IPv6 security comment will thank you for that 😉
Best
Enno
Continue readingI just had an interesting discussion with Jim Small (who gives the “IPv6 Attacks and Countermeasures” talk at the North American IPv6 Summit next week) about the feasibility of the “undetermined-transport” keyword in PACLs on Cisco 3560 switches (here running IOS 15.0(2)SE). Actually there’s some kind-of funny behavior as for it on that platform (and there’s even some Cisco documentation stating it’s not supported). Let’s have a look, and start with a quick refresher.
Rogue router advertisements pose a significant security and network stability risk in IPv6 networks. That’s why there’s a security feature implemented on certain switches which is called “RA Guard” (see also here). Unfortunately (at least Cisco’s current implementation of) RA Guard can easily be circumvented, e.g. by using the following command from the THC IPV6 attack toolkit:
fake_router26 -E D eth0
Continue reading “Some more Notes on RA Guard Evasion and “undetermined-transport””
Continue readingIPv6 introduces a lot of new features and consequently, a lot of new capabilities. Obviously, the most significant of them is the huge address space that it offers. However, this is not the only one. IPv6 also introduces the use of the IPv6 Extension Headers. The IPv6 header has been considerably simplified in comparison with IPv4 one. On the other hand, the IPv6 Extension Headers, not only do the “job” of most of the fields which were removed from the main header, but, additionally, they add many more. However, any new “technology” creates new attack opportunities and a “new” protocol, such as IPv6 could not be an exception, especially since its design and implementation is more complicated than it’s predecessor.
Continue reading “IPv6 Extension Headers: New Features, and New Attack Vectors”
It has been a year since fragmentation attacks in IPv6 were last examined publicly (in Black Hat Europe 2012). Issues well known from the IPv4 era appeared again in IPv6. Surprisingly enough, some of the most popular Operating Systems (OS), included ones considered “secure”, were proven to be vulnerable to such attacks, although fragmentation overlapping is strictly forbidden in IPv6 since 2009 (RFC5722). Some other OS, although in a better shape, still appeared to have some issues in specific cases.
But a year has already passed since then and the vendors should have fixed these issues now; or not? Definitely, a significant progress (in some cases) has been made but, is this enough? In the IPv6 Security Summit that will take place during Troopers13, in the “Fragmentation Overlapping Attacks Against IPv6: One Year Later” presentation, various fragmentation overlapping scenarios will be tested to examine if such attacks can still be successful or not. Detailed results of extensive tests will be presented and any non-compliant behaviors will be further discussed regarding the potential security implications.
Continue reading “Fragmentation (overlapping) attacks in IPv6. Have we learned our lesson, yet?”
at first a happy new year to all our readers!
And, of course, to everybody else, too ;-). May 2013 bring good things for you all, in particular (but not only) in the infosec space.
At the recent ATSAC 2012 conference a guy from the CERT Insider Threat Center gave a talk on the exact topic. Given that the ENISA Cloud Computing Risk Assessment lists “Cloud Provider Malicious Insider” as one of the top eight risks (out of overall 35 risks evaluated) and we just had some discussion about this in a customer environment, this might be of interest for some readers.
The slides of the talk can be found here.
best
Enno
Continue readingRecommendations by the German Federal Office for Information Security (BSI – Bundesamt für Sicherheit in der Informationstechnik) are obligatory for German government agencies, civil services and authorities (like recommendations of the NIST are relevant to American government agencies and authorities). They are often used as references and security best practices in other countries as well. Hence it is hard to understand why the recommendations on how to harden Windows Server 2008 based systems were published only some weeks ago and only on a preliminary draft basis (which is, obviously, better than nothing ;-)).
We at ERNW, however, did an overall baseline security approach of Windows Server 2008 R2 and Active Directory for a large German authority last year. The aim was to fullfil the requirements of the German Federal Office for Information Security without having precise technical guidelines by the BSI itself (from our side we do have guidelines of course ;-)). The hardened Windows Server 2008 R2 environment was then approved at the end of 2011 by the German BSI. Now we published the results of our overall approach in our latest newsletter [German language].
Enjoy reading!
Friedwart Kuhn
PS: There’s also a digitally signed version of the newsletter. (Because it is signed with a qualified certificate, the validation requires an appropriate validation software, for example SecSigner from SecCommerce – which is free software).
Continue readingLast week Christopher Werny and I gave a talk on IPv6 Privacy Extensions at the Heise IPv6 Kongress. As our slides were not included in the event’s material here’s the presentation’s slide deck.
As in 2011 we really liked the conference; there was a number of interesting talks and we met quite some fellows from the IPv6 security space. Btw: we plan to organize a dedicated IPv6 security summit in late 2012 (probably on 6th and 7th of November) in Heidelberg, similar to the Telco Sec Day at Troopers. We’ll annouce details as for this one in some weeks.
Stay tuned & have a great week everybody
Enno
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