Security information and event management
Security information and event management (SIEM) is a subsection within the field of computer security, where software products and services combine security information management (SIM) and security event management (SEM). They provide real-time analysis of security alerts generated by applications and network hardware.
The term and the initialism SIEM was coined by Mark Nicolett and Amrit Williams of Gartner in 2005.
The acronyms SEM, SIM and SIEM have sometimes been used interchangeably, but generally refer to the different primary focus of products:
- Log management: Focus on simple collection and storage of log messages and audit trails
- Security information management (SIM): Long-term storage as well as analysis and reporting of log data.
- Security event manager (SEM): Real-time monitoring, correlation of events, notifications and console views.
- Security information and event management (SIEM): Combines SIM and SEM and provides real-time analysis of security alerts generated by network hardware and applications.
- Managed Security Service: (MSS) or Managed Security Service Provider: (MSSP): The most common managed services appear to evolve around connectivity and bandwidth, network monitoring, security, virtualization, and disaster recovery.
- Security as a service (SECaaS): These security services often include authentication, anti-virus, anti-malware/spyware, intrusion detection, Penetration testing and security event management, among others.
In practice many products in this area will have a mix of these functions, so there will often be some overlap – and many commercial vendors also promote their own terminology. Oftentimes commercial vendors provide different combinations of these functionalities which tend to improve SIEM overall. Log management alone doesn’t provide real-time insights on network security, SEM on its own won't provide complete data for deep threat analysis. When SEM and log management are combined, more information is available for SIEM to monitor.
A key focus is to monitor and help manage user and service privileges, directory services and other[clarification needed] system-configuration changes; as well as providing log auditing and review and incident response.
- Data aggregation: Log management aggregates data from many sources, including network, security, servers, databases, applications, providing the ability to consolidate monitored data to help avoid missing crucial events.
- Correlation: Looks for common attributes, and links events together into meaningful bundles. This technology provides the ability to perform a variety of correlation techniques to integrate different sources, in order to turn data into useful information. Correlation is typically a function of the Security Event Management portion of a full SIEM solution
- Alerting: The automated analysis of correlated events
- Dashboards: Tools can take event data and turn it into informational charts to assist in seeing patterns, or identifying activity that is not forming a standard pattern.
- Compliance: Applications can be employed to automate the gathering of compliance data, producing reports that adapt to existing security, governance and auditing processes.
- Retention: Employing long-term storage of historical data to facilitate correlation of data over time, and to provide the retention necessary for compliance requirements. Long term log data retention is critical in forensic investigations as it is unlikely that discovery of a network breach will be at the time of the breach occurring.
- Forensic analysis: The ability to search across logs on different nodes and time periods based on specific criteria. This mitigates having to aggregate log information in your head or having to search through thousands and thousands of logs.
- SIEM visibility and anomaly detection could help detect zero-days or polymorphic code. Primarily due to low rates of anti-virus detection against this type of rapidly changing malware.
- Parsing, log normalization and categorization can occur automatically, regardless of the type of computer or network device, as long as it can send a log.
- Visualization with a SIEM using security events and log failures can aid in pattern detection.
- Protocol anomalies which can indicate a mis-configuration or a security issue can be identified with a SIEM using pattern detection, alerting, baseline and dashboards.
- SIEMS can detect covert, malicious communications and encrypted channels.
- Cyberwarfare can be detected by SIEMs with accuracy, discovering both attackers and victims.
Correlation rules examples.
SIEM systems can have hundreds and thousands of correlation rules. Some of these are simple, and some are more complex. Once a correlation rule is triggered the system can take appropriate steps to mitigate from a cyber attack. Usually, this includes sending a notification to a user and then possibly limiting or even shutting down the system. According to UTMStack, these are some of the most important ones.
Brute Force Detection
Brute force detection is relatively straight forward. Brute forcing relates to continually trying to guess a variable. It most commonly refers to someone trying to constantly guess your password - either manually or with a tool. However, it can refer to trying to guess URLs or important file locations on your system.
An automated brute force is easy to detect as someone trying to enter their password 60 times in a minute is impossible.
When a user logs in to a system, generally speaking, it creates a timestamp of the event. Alongside the time, the system may often record other useful information such as the device used, GPS address, IP address, incorrect login attempts, etc. The more data is collected the more use can be gathered from it. For impossible travel, the system looks at the current and last login date/time and the difference between the recorded distances. If it deems it's not possible for this to happen, for example traveling hundreds of miles within a minute, then it will set off a warning.
Fortunately, many employees and users are now using VPN services, therefore this should be taken into consideration when setting up such a rule.
Excessive File Copying
If you think about your day-to-day activities, you most likely don't copy or move a lot of files around on your system. Therefore any excessive file copying on a system could be attributed to someone wanting to cause harm to your company. Unfortunately, it's not as simple as stating someone has gained access to your network illegally and they want to steal confidential information. It could also be an employee looking to sell company information, or they could just want to take home some files for the weekend.
A DDoS (Distributed Denial of Service) Attack would cause an issue for pretty much any company. A DDoS attack can not only take your web properties offline, it can also make your system weaker. With suitable correlation rules in place, your SIEM should trigger an alert right at the start of the attack so that you can take the necessary precautionary measures to protect your systems.
File Integrity Change
File Integrity and Change Monitoring (FIM) is the process of monitoring the files on your system. Unexpected changes in your system files will trigger an alert as it's a likely indication of a cyber attack.
Alongside correlation rules, it's also possible for SIEM to have models. Models differ somewhat from correlation rules but if implemented correctly can be just as useful. Instead of using a one-to-one correlation, a model requires a number of steps to happen in order to trigger an alert. This usually means a first-time rule followed by an anomalous behavior. This can be as simple as a user logging in from a different location than usual and then carry out a large file transfer.
This can be extremely useful as a single event does not necessarily mean a compromise of an organization's servers or network, it could just be a team member working from a café for a change in scenery.
Handling False Positives
Unfortunately, false positives appear in all walks of life, and this holds true for SIEM. All tools and systems have the possibility to produce a false-positive result. For example, too many failed login attempts can just be an employee forgetting their password and not someone trying to break into the system. It's important that for any triggered events the steps taken are justifiable and of an appropriate measure as you wouldn't want employees getting locked out for hours in such scenarios. 
Some examples of customized rules to alert on event conditions involve user authentication rules, attacks detected and infections detected.
|Repeat Attack-Login Source||Early warning for brute force attacks, password guessing, and misconfigured applications.||Alert on 3 or more failed logins in 1 minute from a single host.||Active Directory, Syslog (Unix Hosts, Switches, Routers, VPN), RADIUS, TACACS, Monitored Applications.|
|Repeat Attack-Firewall||Early warning for scans, worm propagation, etc.||Alert on 15 or more Firewall Drop/Reject/Deny Events from a single IP Address in one minute.||Firewalls, Routers and Switches.|
|Repeat Attack-Network Intrusion Prevention System||Early warning for scans, worm propagation, etc.||Alert on 7 or more IDS Alerts from a single IP Address in one minute||Network Intrusion Detection and Prevention Devices|
|Repeat Attack-Host Intrusion Prevention System||Find hosts that may be infected or compromised
(exhibiting infection behaviors)
|Alert on 3 or more events from a single IP Address in 10 minutes||Host Intrusion Prevention System Alerts|
|Virus Detection/Removal||Alert when a virus, spyware or other malware is detected on a host||Alert when a single host sees an identifiable piece of malware||Anti-Virus, HIPS, Network/System Behavioral Anomaly Detectors|
|Virus or Spyware Detected but Failed to Clean||Alert when >1 Hour has passed since malware was detected, on a source, with no corresponding virus successfully removed||Alert when a single host fails to auto-clean malware within 1 hour of detection||Firewall, NIPS, Anti-Virus, HIPS, Failed Login Events|
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Williams, Amrit (2005-05-02). "Improve IT Security With Vulnerability Management". Retrieved 2016-04-09.
Security information and event management (SIEM)
- Swift, John (26 December 2006). "A Practical Application of SIM/SEM/SIEM, Automating Threat Identification" (PDF). SANS Institute. p. 3. Retrieved 14 May 2014.
...the acronym SIEM will be used generically to refer...
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- The Future of SIEM - The market will begin to diverge
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- Correlation Archived 2014-10-19 at the Wayback Machine
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