Windows Event Logs
Last updated
Last updated
Windows Event Logs are an intrinsic part of the Windows Operating System. Storing parts from different components of the system, ETW providers, services, amongst others.
Event logs are categorized into the following:
Application
System
Security
Other
Accessing the "Event Viewer" in Windows as adminstrator allows us to explore the various logs available.
Default logs are: Application, Security, Setup, System, and Forwarded Events.
Forwarded Events: These are logs forwarded by other machines.
Each entry in the Windows Event Log is an "Event" and contains the following primary components:
Log Name: The name of the event log (e.g., Application, System, Security, etc.).
Source: The software that logged the event.
Event ID: A unique identifier for the event.
Task Category: This often contains a value or name that can help us understand the purpose or use of the event.
Level: The severity of the event (Information, Warning, Error, Critical, and Verbose).
Keywords: Keywords are flags that allow us to categorize events in ways beyond the other classification options. These are generally broad categories, such as "Audit Success" or "Audit Failure" in the Security log.
User: The user account that was logged on when the event occurred.
OpCode: This field can identify the specific operation that the event reports.
Logged: The date and time when the event was logged.
Computer: The name of the computer where the event occurred.
XML Data: All the above information is also included in an XML format along with additional event data.
Find below an indicative (non-exhaustive) list of useful Windows event logs.
Event ID 4624 (New Logon)
Event ID 4688 (Process Created)
(System Shutdown/Restart): This event log indicates when and why the system was shut down or restarted. By monitoring these events, you can determine if there are unexpected shutdowns or restarts, potentially revealing malicious activity such as malware infection or unauthorized user access.
(The Event log service was started): This event log marks the time when the Event Log Service was started. This is an important record, as it can signify a system boot-up, providing a starting point for investigating system performance or potential security incidents around that period. It can also be used to detect unauthorized system reboots.
(The Event log service was stopped): This event log signifies the moment when the Event Log Service was stopped. It is typically seen when the system is shutting down. Abnormal or unexpected occurrences of this event could point to intentional service disruption for covering illicit activities.
(Windows uptime): This event occurs once a day and shows the uptime of the system in seconds. A shorter than expected uptime could mean the system has been rebooted, which could signify a potential intrusion or unauthorized activities on the system.
(Service status change): This event indicates a change in service startup type, which could be from manual to automatic or vice versa. If a crucial service's startup type is changed, it could be a sign of system tampering.
(The audit log was cleared): Clearing the audit log is often a sign of an attempt to remove evidence of an intrusion or malicious activity.
(Antivirus malware detection): This event is particularly important because it logs when Defender detects a malware. A surge in these events could indicate a targeted attack or widespread malware infection.
(Antivirus remediation activity has started): This event signifies that Defender has begun the process of removing or quarantining detected malware. It's important to monitor these events to ensure that remediation activities are successful.
(Antivirus remediation activity has succeeded): This event signifies that the remediation process for detected malware has been successful. Regular monitoring of these events will help ensure that identified threats are effectively neutralized.
(Antivirus remediation activity has failed): This event is the counterpart to 1119 and indicates that the remediation process has failed. These events should be closely monitored and addressed immediately to ensure threats are effectively neutralized.
(Successful Logon): This event records successful logon events. This information is vital for establishing normal user behavior. Abnormal behavior, such as logon attempts at odd hours or from different locations, could signify a potential security threat.
(Failed Logon): This event logs failed logon attempts. Multiple failed logon attempts could signify a brute-force attack in progress.
(A logon was attempted using explicit credentials): This event is triggered when a user logs on with explicit credentials to run a program. Anomalies in these logon events could indicate lateral movement within a network, which is a common technique used by attackers.
(A handle to an object was requested): This event is triggered when a handle to an object (like a file, registry key, or process) is requested. This can be a useful event for detecting attempts to access sensitive resources.
(Special Privileges Assigned to a New Logon): This event is logged whenever an account logs on with super user privileges. Tracking these events helps to ensure that super user privileges are not being abused or used maliciously.
(A scheduled task was created): This event is triggered when a scheduled task is created. Monitoring this event can help you detect persistence mechanisms, as attackers often use scheduled tasks to maintain access and run malicious code.
& (A scheduled task was enabled/disabled): This records the enabling or disabling of a scheduled task. Scheduled tasks are often manipulated by attackers for persistence or to run malicious code, thus these logs can provide valuable insight into suspicious activities.
(A scheduled task was updated): Similar to 4698, this event is triggered when a scheduled task is updated. Monitoring these updates can help detect changes that may signify malicious intent.
(System audit policy was changed): This event records changes to the audit policy on a computer. It could be a sign that someone is trying to cover their tracks by turning off auditing or changing what events get audited.
(A user account was changed): This event records any changes made to user accounts, including changes to privileges, group memberships, and account settings. Unexpected account changes can be a sign of account takeover or insider threats.
(Kerberos pre-authentication failed): This event is similar to 4625 (failed logon) but specifically for Kerberos authentication. An unusual amount of these logs could indicate an attacker attempting to brute force your Kerberos service.
(The domain controller attempted to validate the credentials for an account): This event helps track both successful and failed attempts at credential validation by the domain controller. Multiple failures could suggest a brute-force attack.
(Antivirus real-time protection configuration has changed): This event indicates that the real-time protection settings of Defender have been modified. Unauthorized changes could indicate an attempt to disable or undermine the functionality of Defender.
(A network share object was accessed): This event is logged whenever a network share is accessed. This can be critical in identifying unauthorized access to network shares.
(A network share object was added): This event signifies the creation of a new network share. Unauthorized network shares could be used to exfiltrate data or spread malware across a network.
(A network share object was checked to see whether client can be granted desired access): This event indicates that someone attempted to access a network share. Frequent checks of this sort might indicate a user or a malware trying to map out the network shares for future exploits.
(The Windows Filtering Platform has blocked a connection): This is logged when the Windows Filtering Platform blocks a connection attempt. This can be helpful for identifying malicious traffic on your network.
(A service was installed in the system): A sudden appearance of unknown services might suggest malware installation, as many types of malware install themselves as services.