Cybersecurity in Plain English: What is a SIEM?

I’ve written a blog series like this for many companies I’ve worked for, now I’m doing it on my own blog for everyone to read. Please drop me questions you’d like answered to me via Twitter/X/whatever it’s called this week @miketalonnyc – I’d love to get you answers explained without the jargon! 

As more organizations beef up their cybersecurity resilience, many new tools and platforms become part of organizational operations. This has led to several contacts of mine asking, “What is a SIEM, and what does it do for cybersecurity, and how the heck do you pronounce it?” Let’s dive in and find out.

A Security Incident and Event Management (SIEM) platform is a tool-set used to bring together information from applications, systems, services, hardware, and other operational components into one place so that all of that information can be used to try to find cybersecurity incidents taking place. Think of it as a gigantic database that pulls in data from hundreds or thousands of sources within the organization and from threat intelligence feeds. Coupled with that database, a SIEM includes systems to remove redundant information and process all the information to look for points of correlation – sequences of events that, when viewed together, indicate something is going on. As for pronunciation, there is a difference of opinion on that. The two top pronunciations are sim (as in simulation or simple) and seem (as in seemingly or seams). Either is generally accepted by the technology community. 

The first step in SIEM operations is ingestion – pulling in data from multiple sources and de-duplicating it. SIEM solutions integrate with thousands of different tools and platforms to ingest data. These can include things like Active Directory and other Identity and Access Management (IAM) systems, hardware platforms, cybersecurity tools like firewalls, anti-malware, and others, Operating System and application logging systems, and quite a large number of other sources. All this information is brought into a de-duplication system that removes redundant data-points to reduce the amount of information being sent into the database for correlation. Because of the sheer number of logs and events being ingested and de-duplicated, SIEM solutions must be highly robust and capable of dealing with massive amounts of data at once, and therefore are typically cloud-based solutions where they can be elastic – able to expand to use more resources as needed, but contract and reduce the amount of resources they use when the extra capacity isn’t needed to reduce costs. 

Once data is being ingested efficiently and de-duplicated, the second phase of SIEM operations – correlation – takes place. Correlation is a real-time operation which looks at the sum total of ingested information to attempt to define patterns within that data which indicate threat activity. For example, odd network behavior alone could be indicative of a threat, but could also be indicative of a user doing something unusual without malicious intent. A SIEM would attempt to correlate that network behavior with other indicators of threat activity; such as an anti-malware tool discovering software attempting to access privileged information, or an IAM system recognizing multiple attempts at privilege elevation (a user or process attempting to gain administrator access to something). Taken individually, these actions may not be malicious or even suspicious – the escalation could be a misconfigured application, and the malware could be a one-off download of something that isn’t recurring or able to impact the organization. But, when correlated together, they indicate that something is going on which is indeed suspicious at the very least.  

SIEM platforms also tie into ticketing and email systems to alert IT and cybersecurity staff when correlated events indicate threat activity is going on. These staffers can then block access, undo changes, prepare incident reports, etc. Many SIEM solutions can also work with Security Orchestration, Automation, and Response (SOAR) platforms to take direct action, but these platforms currently have limitations whenever there is more than one valid action to take, making human staffers a necessary part of the process for many types of incidents. 

Overall, SIEM solutions are an invaluable resource. Through de-duplication of data, correlation of potential or actual threat activity, and the ability to alert staff and SOAR platforms in real time, SIEM solutions act as a massive force-multiplier for organizations. They allow for accurate and timely detection and response to security incidents that would not be possible via manual operations, and keep organizations safer and more resilient without creating massive amounts of staff burnout along the way.