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What Is SIEM? A Brilliant Guide to the Basics

October 23, 2020


Safeguarding your organization's cybersecurity is tricky.

You need skillful security researchers and analysts to monitor potential risks and mitigate them before an impact. But when threat actors are continually revamping methods to slip past you, even a minute security gap or negligence can compromise your security posture.

To avoid it, you must bestow undivided attention to your IT infrastructure and prevent it from security threats. It's indispensable, and technology like Security Information and Event Management (SIEM) software makes it easy.

On an enterprise network, SIEM systems have two primary functions. First, they act as a secure and centralized point for collecting all log entries from systems, network devices, and applications, preventing unauthorized access. The second functionality of SIEM systems includes applying artificial intelligence to correlate these log entries and detect patterns of potentially malicious activity.

"From logging and monitoring to investigation and analysis, SIEM tools are integral to security ecosystems of all sizes."

Aaron Walker
Research Principal, Cybersecurity at G2

Undoubtedly, SIEM systems have access to all log entries across the organization, enabling it to identify security threats that may go unnoticed if signs of cyber attack are spread through multiple departments. 

In a hierarchical organization, network engineers might have access to firewall logs, system engineers can access operating system logs, and application logs are visible to application managers. Due to this siloed approach, every department can see only a piece of the puzzle. But SIEM considers the puzzle as a whole; it then applies log correlation to identify a pattern that may converge into a security threat.

Example: If event 'X' and event 'Y' happen at the same time, followed by an event 'Z,' the SIEM solution notifies the IT admin. Whenever an issue is detected, the SIEM system might log additional information, trigger an alert, or command other security controls to stop an activity's progress.

How does SIEM work?

SIEM systems deploy multiple collection agents in a hierarchical manner to aggregate event data generated by host systems, network equipment, antivirus, or other security devices in the IT infrastructure.

Once these logs are in the collectors, they are sent to SIEM's centralized management console. These log entries are then placed in categories such as malware activity, failed login attempt, potentially malicious activity, and exploits.

With the help of event correlation rules, the SIEM solution connects the dots and checks the individual event or a combination that can lead to security breaches.

For eg., if someone tries to log-in 10 times in five minutes and fails, it's possible that they have forgotten the password and SIEM sets it in lower priority. But if there are 100 unsuccessful login attempts in 10 minutes, it could indicate a brute-force attack. SIEM flags such events with a high severity tag and alerts the concerned authority.

What are the use cases of SIEM?

SIEM solutions are primarily used for security monitoring and maintaining a centralized point for all logs for compliance purposes. Here are various other use cases of SIEM. Let’s delve into them one by one.

Security monitoring

SIEM solutions help in real-time threat monitoring of security events in an organization. As it has access to multiple data sources, SEIM can quickly notice patterns in events that can put up a cybersecurity risk.

It helps security professionals to monitor the IT infrastructure continuously while providing them access to a centralized repository of log entries. It enables them to identify events that may appear harmless individually but when occurred in a combination; they may converge into a cyber attack.

IoT security

The growing adoption of Internet of Things (IoT) devices connected across the internet has led to increasing entry points from where a hacker can penetrate your network.

In an effort to prevent such events, IoT solution vendors provide Application Programming Interfaces (APIs) and external data repositories that can be integrated into a SIEM solution. It helps mitigate IoT threats such as a denial-of-service (DoS) attack and more, making SIEM and integral part of your security posture.

Identifying insider threats

SIEM uses its advanced threat detection capabilities to identify malicious insiders by using browser forensics, network data, and event log indicating a plan of a cyber attack. In some businesses, SIEM carries on granular monitoring of privilege accounts and triggers alerts for actions an end-user is not allowed to perform, like disabling security software.

Advanced threat detection

SIEM systems recognize data exfiltration (unauthorized transfer of sensitive data outside the organization) and can pick up signals of data transfer in abnormal sizes, frequency, and payload. It also helps identify advanced persistent threats (APTs) by detecting warning signals of an outside entity carrying a focused attack or a long term campaign to breach your cybersecurity.

Digital forensics and incident response

SIEM systems alert security analysts whenever a security incident is taking place. It enables you to realize the severity of the incident and create prompt remediation measures. SIEM software has complete access to all logs that security analysts can use to collect information they need and get digital forensics during a security incident and reduce response time.

Compliance and Reporting

SIEMs provide reporting, which is essential to meet the regulatory standard of HIPAA, PCI DSS, SOX, FERPA, and so on. It helps an organization prove to auditors and regulators that proper safeguards are in place, and security incidents are identified and managed.

Evolution of SIEM

The IT department gets many alerts generated by the intrusion detection and prevention systems (IDPS). SIEM was initially developed to deal with a large number of these alerts.

It originally evolved from the log management discipline and has expanded its scope to include a combination of security event management (SEM) and security information management (SIM). With this combination, SEIM provides a real-time analysis of security alerts generated by the application and network hardware.

Generally, SEIM is used to identify security issues, log security data, manage incidents, and for compliance reporting purposes. In fact, Payment Card Industry Data Security Standard (PCI DSS) drove SIEM adoption in large enterprises, and slowly smaller organizations made their strides.

Today, SIEM solutions have evolved considerably to include advanced techniques like User Behavior Analytics (UBA), Deep Packet Inspection and Security Orchestration, Automation, and Response (SOAR). UBA uses algorithms based on machine learning and works on a predictive model. It has replaced the rule-based algorithms to increase overall efficiency and help the organization for effective threat detection.

Managed SIEM solutions have emerged for small businesses, where SMBs with limited resources can also benefit from its advanced machine learning capabilities, behavioral analytics, and other services.

In times of cyberattack, large businesses have resources to mitigate the damages, whereas SMBs generally don't have the same at their disposal. Managed SIEM for small businesses helps them protect their assets during such situations.

What do SIEM systems offer?

SIEM systems combine security event management and security information management to provide a complete solution for monitoring information security. 

The critical focus of SIEM systems is to maintain a repository of all log entries in your organization and provide comprehensive visibility over your systems, network, applications, and other devices, and alert when there is a potentially malicious activity.

SIEM systems present the users with the following capabilities:

  • Data aggregation enables you to accumulate data from various sources and gain an overview of all log entries from different departments.
  • Correlation technique identifies patterns in occurrences of events that lead to cyber attacks. It helps to turn data from different sources into useful information to identify common attributes and links between events that collectively pose a security threat.
  • Alerting notifies the security professional whenever a correlation rule is triggered.
  • Dashboards present data in information charts for events that do not follow a standard pattern and develop a visualization.
  • Forensic analysis helps to search logs on different nodes and time periods for incident response management. It enables you to avoid the tedious workflow of searching through a large number of logs in critical situations.
  • Compliance automates the collection of data and creates audit-ready reports according to the existing regulatory standards.
  • Retention helps store logs for an extended period of time to facilitate the correlation of data over time. Long-term data retention proves as a critical asset during forensic investigations.

Top 5 SIEM tools

Security information and event management software combines a variety of security software components into one platform. It provides a centralized access point to IT and security teams to access the same information and alerts for more effective communication and planning.

To qualify for inclusion in the SIEM category, a product must:

  • Aggregate and store IT security data.
  • Assist in user provisioning and governance.
  • Identify vulnerabilities in systems and endpoints.
  • Monitor for anomalies within an IT system.

* Below are the five leading SIEM software from G2's Fall 2020 Grid® Report. Some reviews may be edited for clarity.

1. Splunk Enterprise Security

Splunk Enterprise Security is an analytics-driven SIEM solution that combats threats with analytics-driven threat intelligence feeds. It enables you to detect, investigate, and respond in real-time while streamlining your security stack, minimizing unplanned downtime with increased transparency all in one platform.

What users like:

"It's an enterprise-level tool for log aggregation and management that enables an all inclusive approach to data mining for service management and compliance."

- Splunk Enterprise Security Review, Scott R.

What users dislike:

"The UI can be more interactive, and they can also be little competitive with pricing as the one-year option costs a fortune as an organization, making it tough for small startups to afford this tool."

- Splunk Enterprise Security Review, Ashok V.

2. IBM Security QRadar

IBM Security QRadar helps security professionals to detect, understand, and prioritize threats that pose a risk to your organizations' cybersecurity. The solution captures data from asset, cloud, network, endpoint, and users to correlate it against vulnerability information and threat intelligence. It applies advanced analytics to identify and track threats as they progress in the kill chain.

What users like:

"The first noticeable thing is the GUI of the tool, which is easy to operate. Dashboard configuration is exemplary, where it's easy to monitor traffic in a single frame with a visual format. You can add multiple parameters for log searching. It also provides an ability to integrate with other solutions with good technical support and documentation.

"You can add multiple log sources easily and use features like User Analytics Behavior. It's useful in monitoring email trace logs after trace log source integration in large-sized organizations. Rule creation is easy, and building block features are good."

- IBM Security QRadar Review, Tejas S.

What users dislike:

"User Interface is one of the essential components when it comes to any SIEM solution. The user interface needs some improvements to enhance user experience. Maybe HTML5 based additions will be a good value add.

"Also, the reporting component becomes a bit confusing sometimes, and it's also not easy to do, so it needs some improvements in the future."

- IBM Security QRadar, Muhammad Irfan MS I.

3. LogRhythm NextGen SIEM Platform

LogRhythm NextGen SIEM platform delivers comprehensive security analytics, user and entity behavior analytics (UEBA); network detection and response (NDR); and security orchestration, automation, and response (SOAR) within a single, integrated platform for rapid detection, response, and neutralization of threats. It empowers more than 4000 customers globally to advance their security operations.

What users like:

"LogRhythm, like any other SIEM, can be a complicated platform. Having used two other SIEM platforms, LogRhythm has one of the most streamlined configurations and overall usability. The SIEM comes with both a thick-client and web interface. The thick-client is comprehensive, while the web interface features common capabilities such as dashboards, and SOAR."

- LogRhythm NextGen SIEM Platform Review, Dave D.

What users dislike:

"Its power and flexibility can be overwhelming at times, but this is the nature of a mature SIEM solution, and there is always LogRhythm Support or 3rd party implementation services available to assist with any query."

- LogRhythm NextGen SIEM Platform Review, Mark S.

4. Sumo Logic

Sumo Logic broadly addresses challenges that emerge with digital transformation, modern applications, and cloud computing while being a pioneer of continuous intelligence.

What users like:

"Sumo Logic is a cloud-based platform that simplifies analysis and automatic data collection to obtain the necessary information. It provides a quality and improved experience to our clients in the application. The security tools and functions allow us to carry out supervision and accelerate the delivery of modern applications, in addition to being able to solve any inconvenience or problem in real-time, this allows us to have a stable and reliable security solution."

- Sumo Logic Review, Nancy J.

What users dislike:

"The tool performs its job very well, but there is a steep learning curve before you can start taking advantage of the advanced features and optimizations which the SIEM tool can offer. Querying is relatively tough, and you need to brush up your skills to write complex and useful queries.

"The GUI can be improved and made cleaner with only the required options in a single view and not everything put in front of you, of which you are not even aware and probably would never use." 

- Sumo Logic Review, Shilpa M.

5. AlienVault USM (from AT&T Cybersecurity)

AlienVault USM Anywhere (from AT&T Cybersecurity) is a security management solution based on the cloud that accelerates and centralizes threat detection, compliance management, incident management for your cloud, hybrid cloud, and on-premises environments.

What users like:

"We like the ease of use and customization of USM. It’s a work horse; no matter what devices or the number of logs we throw at it, the system processes them in real-time, correlates the events, and alerts only those events that need human review. USM Anywhere is a great progression of the product. Whether you are a small business with no security team or a large enterprise with a large team, AlienVault will meet your needs."

- AlienVault USM Review, Karl H.

What users dislike:

"Some features are unavailable that are available in other SIEM tools such as the use of advanced searching languages, custom correlation rules, and custom parsers."

- AlienVault USM Review, Joe L.

Reinforce your cybersecurity with SIEM tools

SIEM tools will help your team closely monitor IT assets and detect every possible security gap or malicious activity that could welcome a threat. It would help you avoid a security breach and ensure that you adhere to the latest compliance standards. 

Find out all you need to know about compliance audits now and save yourself from paying hefty fines.

SIEM software
Keep a steady focus on your security posture

Use SIEM tools to monitor logs and detect patterns of potentially malicious activity.

SIEM software
Keep a steady focus on your security posture

Use SIEM tools to monitor logs and detect patterns of potentially malicious activity.

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