Event log management is a critical skill to learn in all Windows environments. Activity is being recorded to Windows event logs every second and it acts as not only a security tool but also as a vital troubleshooting aid. With a feature called Windows Event Forwarding (WEF), Windows can send events to the Windows event collector from remote machines.
Event Log Forwarding
WEF is a service that allows you to forward events from multiple Windows servers and collect them in one spot. The service has two main components; a forwarder and a collector. A collector is a service running on a Windows server that collects all events sent to it from an event log forwarder.
The next step is to configure one or more Windows servers to begin forwarding event logs to the collector. The easiest way to do so is by creating a GPO. This GPO can then be applied to one or more OUs which contain the servers to send events from.
Note: Many of the event logs in Windows Server already provide the Network Service account access to the common event logs like Application and System. But the account is not given access to the Security event log and other custom event logs.
1. Begin by opening up a command prompt and running wevtutil gl security. This will provide various information about the Security event log. But the piece to pay attention to is the channelAccess SDDL.
6. Click Advanced in the Subscription Properties window. Now select Minimize Latency. This setting will ensure the collector will receive events as soon as possible and also to help it catch up if it gets behind.
For ATA versions 1.8 and higher, event collection configuration is no longer necessary for ATA Lightweight Gateways. The ATA Lightweight Gateway now read events locally, without the need to configure event forwarding.
To enhance detection capabilities, ATA needs the following Windows events: 4776, 4732, 4733, 4728, 4729, 4756, 4757, 7045. These can either be read automatically by the ATA Lightweight Gateway or in case the ATA Lightweight Gateway is not deployed, it can be forwarded to the ATA Gateway in one of two ways, by configuring the ATA Gateway to listen for SIEM events or by configuring Windows Event Forwarding.
After configuring port mirroring from the domain controllers to the ATA Gateway, use the following instructions to configure Windows Event forwarding using Source Initiated configuration. This is one way to configure Windows Event forwarding.
To accomplish this functionality, there are two different subscriptions published to client devices - the Baseline subscription and the suspect subscription. The Baseline subscription enrolls all devices in your organization, and a Suspect subscription only includes devices that have been added by you. The Suspect subscription collects more events to help build context for system activity and can quickly be updated to accommodate new events and/or scenarios as needed without impacting baseline operations.
This implementation helps differentiate where events are ultimately stored. Baseline events can be sent to devices with online analytical capability, such as Security Event Manager (SEM), while also sending events to a MapReduce system, such as HDInsight or Hadoop, for long-term storage and deeper analysis. Events from the Suspect subscription are sent directly to a MapReduce system due to volume and lower signal/noise ratio, they're largely used for host forensic analysis.
Event generation on a device must be enabled either separately or as part of the GPO for the baseline WEF implementation, including enabling of disabled event logs and setting channel permissions. For more info, see Appendix C - Event channel settings (enable and channel access) methods. This condition is because WEF is a passive system regarding the event log. It can't change the size of event log files, enable disabled event channels, change channel permissions, or adjust a security audit policy. WEF only queries event channels for existing events. Additionally, having event generation already occurring on a device allows for more complete event collection building a complete history of system activity. Otherwise, you'll be limited to the speed of GPO and WEF subscription refresh cycles to make changes to what is being generated on the device. On modern devices, enabling more event channels and expanding the size of event log files hasn't resulted in noticeable performance differences.
The longer answer is: The Eventlog-forwardingPlugin/Operational event channel logs the success, warning, and error events related to WEF subscriptions present on the device. Unless the user opens Event Viewer and navigates to that channel, they won't notice WEF either through resource consumption or Graphical User Interface pop-ups. Even if there's an issue with the WEF subscription, there's no user interaction or performance degradation. All success, warning, and failure events are logged to this operational event channel.
A WEF subscription can be configured to be pushed or pulled, but not both. The simplest, most flexible IT deployment with the greatest scalability can be achieved by using a push, or source initiated, subscription. WEF clients are configured by using a GPO and the built-in forwarding client is activated. For pull, collector initiated, the subscription on the WEC server is pre-configured with the names of the WEF Client devices from which events are to be selected. Those clients are to be configured ahead of time to allow the credentials used in the subscription to access their event logs remotely (normally by adding the credential to the Event Log Readers built-in local security group.) A useful scenario: closely monitoring a specific set of machines.
The WEC server maintains in its registry the bookmark information and last heartbeat time for each event source for each WEF subscription. When an event source reconnects to a WEC server, the last bookmark position is sent to the device to use as a starting point to resume forwarding events. If aWEF client has no events to send, the WEF client will connect periodically to send a Heartbeat to the WEC server to indicate it's active. This heartbeat value can be individually configured for each subscription.
In a domain setting, the connection used to transmit WEF events is encrypted using Kerberos, by default (with NTLM as a fallback option, which can be disabled by using a GPO). Only the WEF collector can decrypt the connection. Additionally, the connection between WEF client and WEC server is mutually authenticated regardless of authentication type (Kerberos or NTLM.) There are GPO options to force Authentication to use Kerberos Only.
When the event log overwrites existing events (resulting in data loss if the device isn't connected to the Event Collector), there's no notification sent to the WEF collector that events are lost from the client. Neither is there an indicator that there was a gap encountered in the event stream.
The primary difference is in the latency which events are sent from the client. If none of the built-in options meet your requirements, you can set Custom event delivery options for a given subscription from an elevated command prompt:
Yes. If you desire a High-Availability environment, configure multiple WEC servers with the same subscription configuration and publish both WEC Server URIs to WEF clients. WEF Clients will forward events simultaneously to the configured subscriptions on the WEC servers, if they have the appropriate access.
There are three factors that limit the scalability of WEC servers. The general rule for a stable WEC server on commodity hardware is planning for a total of 3,000 events per second on average for all configured subscriptions.
Disk I/O. The WEC server doesn't process or validate the received event, but rather buffers the received event and then logs it to a local event log file (EVTX file). The speed of logging to the EVTX file is limited by the disk write speed. Isolating the EVTX file to its own array or using high speed disks can increase the number of events per second that a single WEC server can receive.
Network Connections. While a WEF source doesn't maintain a permanent, persistent connection to the WEC server, it doesn't immediately disconnect after sending its events. This leniency means that the number of WEF sources that can simultaneously connect to the WEC server is limited to the open TCP ports available on the WEC server.
The subscription is essentially a collection of query statements applied to the Event Log. This subscription means that it's modular in nature and a given query statement can be removed or changed without impacting other query statement in the subscription. Additionally, suppress statements that filter out specific events, only apply within that query statement and aren't to the entire subscription.
To gain the most value out of the baseline subscription, we recommend having the following requirements set on the device to ensure that the clients are already generating the required events to be forwarded off the system.
If your organizational audit policy enables more auditing to meet its needs, that is fine. The policy below is the minimum audit policy settings needed to enable events collected by both baseline and targeted subscriptions.
The recommended and most effective way to do this customization is configuring the baseline GPO to run a scheduled task to configure the event channels (enable, set maximum size, and adjust channel access). This configuration will take effect at the next GPO refresh cycle and has minimal impact on the client device.
There are several types of event logs maintained by the Windows operating system. One of these is the Forwarded Events event log. This log records events written by other computers in the same network ("source computers") that have forwarded their events to the "collector computer." By using the Forwarded Events log, you can keep track of the event logs of several other computers from one central location.
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