Security Information and Event Management (SIEM): The Big Picture
What is SIEM?
The main focus of SIEM is reporting security-related incidents and events, across an organization’s IT infrastructure. For example, succeeded or failed logins, malware activities, or escalation of privileges. SIEM platforms combine SIM and SEM:
- SIM focuses on collecting and storing historical log data for analysis
- SEM focuses on real-time events
SIEM integrates both, consolidating historical log data with real-time events and creating correlations that assist security teams in detecting anomalies, vulnerabilities, and incidents.
What are SIEMs used for?
SIEMs provide centralized security monitoring and analysis, allowing organizations to efficiently detect, investigate, and address security threats. But to be more specific, SIEMs are used for many things.
Collect and Aggregate Data
SIEMs collect and aggregate log and event data from various IT infrastructure sources, such as servers, firewalls and applications.
Monitor Security Events
SIEMs assist with real-time monitoring of organizational systems for security incidents. By accessing multiple data sources, a SIEM offers a unique view of security events. It enables security teams to detect incidents that individual security tools may miss and prioritize alerts with the most significant implications.
Advanced Threat Detection
SIEMs can help detect, mitigate and prevent advanced threats, including:
- Malicious insiders: A SIEM can leverage browser forensics, network data, authentication logs and other information to detect insiders attempting or executing an attack.
- Data exfiltration: A SIEM can identify unusual data transfers in terms of size, frequency, or content, indicating the illicit transfer of sensitive information outside the organization.
- External threats, including advanced persistent threats (APTs): A SIEM can recognize early indicators of a targeted attack or prolonged campaign being carried out by an external entity against the organization.
Forensics and Incident Response
SIEMs assist security analysts in identifying ongoing security incidents, triaging the event, and outlining immediate remediation steps. Even when an incident is known, gathering data to fully understand and halt the attack takes time. SIEMs can automatically collect this data, greatly reducing response time. For historical breaches or incidents that require investigation, SIEMs offer detailed forensic data to help trace the attack's origin, identify threat actors, and guide mitigation efforts.
Compliance Reporting and Auditing
SIEMs assist organizations in demonstrating to auditors and regulators that they have the necessary safeguards in place and that security incidents are identified and managed. SIEMs can automate report generation, helping organizations fulfill regulatory compliance requirements such as PCI-DSS, GDPR, etc.
How does SIEM Work?
A SIEM system works by collecting, normalizing, and aggregating security-related data from various sources across an organization, such as servers, firewalls, and applications. It then makes this data easier to understand by putting it into a standard format. Once the data is gathered, the SIEM looks for patterns or unusual activities that might signal a security problem. If something suspicious is found, it sends alerts to the security team. Security analysts review these alerts to figure out what happened and how serious it is. SIEMs can also automate some responses, like blocking harmful IP addresses, to act quickly.
SIEMs help with reporting to meet legal and industry requirements, such as GDPR, PCI-DSS, etc. After an incident, they can help investigate the attack by looking at the details, timeline, and methods used. Finally, SIEMs improve over time by adjusting their settings based on past incidents, making it better at spotting and responding to future threats.