In the past couple of years, cloud-based solutions have gone from the status of a brave new technology to a mainstream vehicle for delivering storage, application, infrastructure and other services. From a security point of view, consuming cloud-based services usually involves delegating security for the service to the service provider. This does not need to be as scary as it sounds – as long as you approach the service engagement with your eyes open, and arm yourself with pertinent requirements for the service provider to provide appropriate controls to protect your organization.
Employees of every organization use a variety of computing devices such as desktops, servers, laptops, security appliances, and mobile devices to increase productivity in this ever-changing world of Information Technology. The confidentiality, integrity, and availability (CIA) of information has become essential to success and often a competitive advantage. A comprehensive patch management process should be a major component to protecting CIA on computing devices and the data they store or transmit. Patch management is not always a simple task, as organizations may have a variety of platforms and configurations, along with other challenges that make patching these components very difficult. However, there are recommendations and best practices to minimize the complexity of this much-needed task.
On October 22, 2013, Cisco TRAC Threat Researcher Martin Lee wrote about Distributed Denial of Service (DDoS) attacks that leverage the Domain Name System (DNS) application protocol. As Martin stated, the wide availability of DNS open resolvers combined with attackers’ ability to falsify the source of User Datagram Protocol (UDP) packets creates a persistent threat to network operators everywhere.
The Great Correlate Debate
SIEMs have been pitched in the past as “correlation engines” and their special algorithms can take in volumes of logs and filter everything down to just the good stuff. In its most basic form, correlation is a mathematical, statistical, or logical relationship between a set of different events. Correlation is incredibly important, and is a very powerful method for confirming details of a security incident. Correlation helps shake out circumstantial evidence, which is completely fair to use in the incident response game. Noticing one alarm from one host can certainly be compelling evidence, but in many cases it’s not sufficient. Let’s say my web proxy logs indicate a host on the network was a possible victim of a drive-by download attack. The SIEM could notify the analysts team that this issue occurred, but what do we really know at this point? That some host may have downloaded a complete file from a bad host – that’s it. We don’t know if it has been unpacked, executed, etc. and have no idea if the threat is still relevant. If the antivirus deleted or otherwise quarantined the file, do we still have anything to worry about? If the proxy blocked the file from downloading, what does that mean for this incident?
This is the problem that correlation can solve. If after the malware file downloaded we see port scanning behavior, large outbound netflow to unusual servers, repeated connections to PHP scripts hosted in sketchy places, or other suspicious activity from the same host, we can create an incident for the host based on our additional details. The order is important as well. Since most attacks follow the same pattern (bait, redirect, exploit, additional malware delivery, check-in), we tie these steps together with security alarms and timestamps. If we see the events happening in the proper order we can be assured an incident has occurred.
Security information and event management systems (SIEM, or sometimes SEIM) are intended to be the glue between an organization’s various security tools. Security and other event log sources export their alarms to a remote collection system like a SIEM, or display them locally for direct access and processing. It’s up to the SIEM to collect, sort, process, prioritize, store, and report the alarms to the analyst. It’s this last piece that is the key to an effective SIEM deployment, and of course the most challenging part. In the intro to this blog series I mentioned how we intend to describe our development of a new incident response playbook. A big first step in modernizing our playbook was a technology overhaul, from an outdated and inflexible technology to a modern and highly efficient one. In this two-part post, I’ll describe the pros and cons of running a SIEM, and most importantly provide details on why we believe a log management system is the superior choice.
Deploying a SIEM is a project. You can’t just rack a new box of packet-eating hardware and expect it to work. It’s important to understand and develop all the proper deployment planning steps. Things like scope, business requirements, and engineering specifications are all factors in determining the success of the SIEM project. Event and alarm volume in terms of disk usage, and retention requirements must be understood. There’s also the issue of how to reliably retrieve remote logs from a diverse group of networked devices without compatibility issues. You must be able to answer questions like: Read More »