Linux


In letzter Zeit häufen sich mal wieder die Angriffe auf Webseiten, bevorzugt Shops. Die Masche der Erpresser läuft meist so, den DDoS Angriff per Email anzukündigen um vorab ein “Schutzgeld” zu erpressen. Näheres wusste bereits der Spiegel unter http://www.spiegel.de/netzwelt/web/0,1518,701879,00.html zu berichten.

Im Gegensatz zum Spiegel Artikel, welcher meist von Säberasseln ausgeht, und eher auf die Trittbrettfahrer abzielt, ist die Bedrohung durchaus real, da sich bereits mit einem Server und ein wenig Perl entsprechend ungeschützte Webserver aus dem Rennen nehmen lassen. Einer der Vertreter dieser Angriffsschnecken, wie ich sie nenne, ist Slowloris, aber es gibt auch andere die ähnlich arbeiten.

Da Slowloris ohne Probleme frei verfügbar ist unter http://ha.ckers.org/slowloris/ , kann jeder halbwegs versierte ITler so einen Angriff starten, sei es zu Kontrollzwecken ob die eigene Infrastruktur vor solchen Angriffen geschützt ist, oder auch zu kriminellen Zwecken, wie der oben genannten Erpressungsweise. Anfällig für solche Angriffe sind zum Beispiel die meisten Apache Server, alte Nginx Versionen und auch diverse andere Webserverplattformen.

In größeren lastverteilten Systemen welche Hardware Balancer nutzen und die korrekt konfiguriert sind, tritt das Problem eher weniger auf, da diese meist von Haus auf ein sogenanntes Late Binding vornehmen, und gegen die meisten dieser Angriffe schützen. Anders sieht es bei alleine im Netz stehenden Servern aus, oder lastverteilten Systemen welche eine Direktverbindung zum Webserver auf dem zum Beispiel ein Apache Server läuft zulassen (IPVS als Beispiel).

Für die letzteren Varianten gibt es aber dennoch diverse Schutzmöglichkeiten. In einem kompletten Setup mit Balancing kann man zum Beispiel als Eintrittstor einen aktuellen NGINX Server nehmen, der auch gleich das SSL Offloading übernehmen kann, aufgrund seiner sehr guten Performance. Dieser greift auf einen HAPROXY zu welcher das Balancing übernimmt. Die eigentlichen Webserver sind am Ende Apache Webserver, welche jedoch mit mod_qos laufen, welches zum Beispiel SLOWLORIS sehr gut abfangen kann.

Die einzelnen Elemente dieser Setups und genauerer Beschreibungen findet man unter den folgenden Links:

Mit diesen Komponenten kann man seine Infrastruktur relativ gut gegen diese Form von Angriffen schützen. Natürlich sollten bei Linuxsystemen von Haus auf zusätzlich TCP_SYNCOOKIES aktiviert sein, um eine andere Angriffsform abzudecken. Distributionen wie aktuelle Fedora oder CentOS haben diesen Parameter bereits als Standardeinstellung aktiviert.

Dann mal erfolgreiches Schützen!


Today I discovered the site of alienvault. Alienvault is a Vendor for Security Information and Event Management (SIEM) Software. alienvault ist the creator if the leading Open Source Security Management tool – OSSIM.

After looking around on their site, I’m quite sure, that I – at least – want to try this thing out.

A few informations about OSSIM in advance, taken from their homepage:

AlienVault Open Source SIEM (OSSIM) is a complete Security Management solution that detects and profiles attacks, and provides a comprehensive, intelligent Security Management platform and toolset.

The entire solution is composed of open source distributions including all seamlessly integrated tools, and the security management platform. The OSSIM project was created and is currently coordinated by the founders of AlienVault.

The OSSIM platform consists of a Management Server, and Sensor or “Probe”. A professional version that includes Logger functionality is also available (please see below). The solution may be implemented as a single monolithic appliance or a set of appliances in which probes are separated from the management server, and distributed throughout the enterprise.

Probes capture network and system information in real time, and send it to the central Management Server where the data is analyzed to assess immediate threats and risk, filter out false positives, and locate false negatives that other security devices and software on the network cannot detect.

Probes not only capture data, but can be tasked as sophisticated attack detection components. They come with several attack detection systems, audit systems, and context learning systems (network profiles, inventory, availability), all of which are seamlessly integrated. When deployed in this fashion probes provide a very quick and safe way of continuously and transparently monitoring local and remote networks, providing provide full visibility of all security related aspects of the enterprise.

The information from the organization’s security systems, such as the firewall, antivirus, IPS, HIDS, etc, are all collected through these probes, and then analyzed through sophisticated intelligence technology. This technology correlates data from many sources to detect blended threats otherwise undetectable by individual systems; prioritize these threats; and make automated decisions with regard to the risk implied in each one.

OSSIM provides a complete management, reporting, and security analysis environment including graphical analysis, incident management workflow, and other tools. This system is capable of monitoring the security of globally distributed networks from a customizable, management console. High level, graphical dashboards are used to progressively drill down to the lowest level of detail.

Of course, there is a commercial version as well, the differences between the Open Source and the Commercial version are as follows:

Logger
The Logger allows for storage of large volumes of data while ensuring its admissibility as evidence in a court of law. The Logger provides an additional database specifically geared for massive, long-term forensic archiving. The Logger collects data in its native format, digitally signs and time-stamps the data, and securely stores it preserving data integrity; whereas the SIEM database is designed for the rapid and versatile analysis required for attack detection and response.

Scalability
AlienVault Professional SIEM allows for both horizontal and vertical load distribution. Horizontal distribution of security information is useful for high performance and high availability configurations. This architectural flexibility also enables highly customizable and scalable management scenarios.

For example, groups of management servers may be organized to create multiple hierarchies of management servers. This sort of architecture facilitates monitoring of large, distributed networks and makes it possible to create various levels of correlation and storage. Each of these hierarchies can then be rolled up into a global view that serves as a central console from which activity on any part of the network can be seen at any time down to the smallest detail.

Performance
AlienVault Professional SIEM is capable of handling very large volumes of data. The engineering team at AlienVault has structured system architecture with multiple optimization and load distribution layers so that the AlienVault Professional SIEM now offers 30 times the performance of OSSIM for any traffic type.

Accountability & Reliability
AlienVault Professional SIEM provides for greater accountability than OSSIM for those organizations that require commercial open source licensing. The commercial license, backed by AlienVault, is accompanied by a comprehensive commercial support and version maintenance offering at extremely competitive rates.

Both OSSIM and AlienVault Professional SIEM are thoroughly tested by AlienVault and the extensive OSSIM community. However, just as with all free open source products, new OSSIM versions that are not entirely stable may at times be released for testing purposes whereas only the most exhaustively tested versions of AlienVault Professional SIEM, which have been vetted for reliability and stability are released to market.

I wil try this thing out and tell you my opinion …….

Hi everybody,


tonite I thought I write about a nice project I was involved in. It’s about bringing the virtual platform for the Developer Kick-Off Meeting 2008 to life. Target of the project is/was to let users around the world participate in a large online event, and even if their where some caveats, we managed to get all the problems solved in time. Users were able to visit the virtual conference center, which was basically a flash application, and join live keynotes, recorded sessions, post comments, communicate via chat, etc.

To manage the expected load, parts of the platform like the videos etc. where distributed via a CDN. The rest of the platform used a mysql master, scale out master, many slaves setup, which performed very well, and of course a horde of apache servers.

Final load tests where done using Funkload. Funkload is a load testing tool I would clearly recommend, and is less bloated like The Grinder or the like.

All in all, our technical project manager Darren Hague of SAP did an exceptional job in this project, keeping track of the timelines and adressing the important issues first. Thanks a lot for this Darren, I really enjoy working with you. Of course, the rest of the team also played their parts very well to get the job done successfully. Thanks alot to you guys too, and hopefully we bring some more visions like this one to life in the future.

Okay, that’s it for tonite, I really need some sleep now ;)

Das Vögelchen hat Recht behalten. DimDim ist jetzt auf der Homepage von DimDim in der Version 4.5 als OpenSource verfügbar. Holt es euch hier

Rumours were right. DimDim Version 4.5 Open Source is now available on their Homepage. You can get it here

Wie mir ein Vögelchen zugetragen hat, kommt morgen die DimDim Version 4.5 Open Source raus. Ich freu mich drauf, denn nachdem die Opensource Variante meist die Features der kommerziellen Version enthielt, dürfte dann auch ein Recording der Webinars und vieles mehr möglich sein. Ich kanns kaum erwarten … :) Hier gibts im übrigen DimDim

Rumours told me, that the Open Source Version of DimDim 4.5 will be released tommorrow. Glad to hear that, because the open source version all the time contained the features of the commercial version, it should be possible to record your webinars then. Can’t await the release ….

Here you can get DimDim