Category: Building

Building
by Florian Grunow

SLES 11 Hardening Guide

SUSE Linux Enterprise Server (SLES) has been around since 2000. As it is designed to be used in an enterprise environment the security of these systems must be kept at a high level. SLES implements a lot of basic security measures that are common in most Linux systems, but are these enough to protect your business? We think that with a little effort you can raise the security of your SLES installation a lot.

We have compiled the most relevant security settings in a SLES 11 hardening guide for you. The guide is supposed to provide a solid base of hardening measures. It includes configuration examples and all necessary commands for each measure. We have split the measures into three categories: Authentication, System Security and Network Security. These are the relevant parts to look for when hardening a system. The hardening guide also includes lists of default services that will help to decide which services to turn off, which is an essential step to minimize the attack surface of your system.

See all of the steps that we compiled for you in our hardening guide for SLES 11: ERNW_Checklist_SLES11_Hardening.pdf

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Building
by Matthias Luft

Basic OS X Hardening & DMA

In the course of a recent endpoint assessment, we also had a OS X 10.8 client system as a target. While we still rely on the Firewire “capability” of unlocking systems on a regular base (using this great tool), we noticed that Apple released a patch to disable Firewire DMA access whenever the system is in a locked state (e.g. with an active screensaver or no user logged in). As we test the Firewire DMA access vulnerability quite often (at least we thought so 😉 ) to prepare for demonstrations in the board room or client assessments, we were quite surprised that we must have actually missed that nice update. In order to verify the effectiveness of the patch, we ran our typical test bed and can quite happily confirm that the update successfully mitigates Firewire DMA access in locked system states.

Beside breaking into unpatched OS X client using Firewire DMA access ;-), we also noticed some lack of hardening guides related to Apples current OS X version 10.8, so we also compiled a basic checklist for OS X hardening measures which we want to share with you:
ERNW_Checklist_OSX_Hardening.pdf

Enjoy,
Matthias

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Building
by Enno Rey

Some Notes on Types of Security Controls & the Way they’re Implemented in Enterprise Environments

Welcome back, Dear Reader,

in this post I’d like to share some reflections on the (potentially inefficient) way some security controls can be observed to be deployed in complex organisations and what this may mean for the future of those controls.

In general the space of security controls can be categorized according to different schemes, such as:

  • By fundamental principle (preventive, detective, reactive, corrective, deterrent, compensating etc. security controls. see for example this overview or this one or some illustration here).
  • By “state of matter” (e.g. components, implementation, operations. again, for some supplemental information look at this one).
  • By type of admission: whitelisting vs. blacklisting (some general discussion here, the respective Schneier-Ranum Face-Off to be found here, and this is only Bruce’s half, but with a number of comments).
  • Related to the overall architecture of implementation: centralized vs. distributed.

For today’s topic I’ll just focus on the latter two and will introduce those shortly.

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Building
by Friedwart Kuhn

EMET v4.0 with New Certificate Trust Feature Released

Microsoft released EMET v4.0  with a new (security) feature that enables protection against fraudulent websites or compromised root certification authorities (do you remember Comodo, DigiNotar, DigiCert, Turktrust et al. ;-)?)

EMET defines via “certificate trust“ a trust chain between the domain name of a website (and its associated website certificate) and a root CA certificate. This is done through so called “pinning rules”. Here is one of the default pinning rules of EMET 4.0 for the domain name login.live.com:

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Building
by Enno Rey

RA Guard (Evasion) – We Stand Corrected

Recently  Jozef PivarnĂ­k and Matěj GrĂ©gr 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

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Building
by Enno Rey

IPv6 Attacks & Pentesting Workshops

Due 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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Building
by Enno Rey

RA Guard Support

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

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Building
by Enno Rey

Some more Notes on RA Guard Evasion and “undetermined-transport”

I 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

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Building
by swengel

IPv6 Extension Headers: New Features, and New Attack Vectors

This is a guest post from Antonios Atlasis

IPv6 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.

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