File access auditing - Amazon FSx for Windows File Server
Audit event log destinationsMigrating your audit controlsViewing event logs

File access auditing

Amazon FSx for Windows File Server supports auditing end-user access to files, folders, and file shares. You can choose to send a file system's audit event logs to other AWS services that offer a rich set of features. These include the enabling querying, processing, storing and archiving logs, issuing notifications, and triggering actions to further advance your security and compliance goals.

For more information about using file access auditing to get insights into access patterns and implement security notifications for end user activity, see File storage access patterns insights and Implementing security notifications for end user activity.

File access auditing enables you to record end-user accesses of individual files, folders, and file shares based on your defined audit controls. Audit controls are also known as NTFS system access control lists (SACLs). If you already have audit controls set up on your existing file data, you can take advantage of file access auditing by creating a new Amazon FSx for Windows File Server file system and migrating your data.

Amazon FSx supports the following Windows audit events for file, folder, and file share accesses:

  • For file accesses, it supports: All, Traverse folder / Execute file, List folder / Read data, Read attributes, Create files / Write data, Create folders / Append data, Write attributes, Delete subfolders and files, Delete, Read permissions, Change permissions, and Take ownership.

  • For file share accesses, it supports: Connect to a file share.

Across file, folder, and file share accesses, Amazon FSx supports logging of successful attempts (such as a user with sufficient permissions successfully accessing a file or file share), failed attempts, or both.

You can configure whether you want access auditing only on files and folders, only on file shares, or both. You can also configure which types of accesses should be logged (successful attempts only, failed attempts only, or both). You can also turn off file access auditing at any time.

Note

File access auditing records end-user access data only from the time it is enabled. That is, file access auditing doesn't generate audit event logs of end-user file, folder, and file share access activity that occurred before file access auditing was enabled.

The maximum rate of access audit events supported is 5,000 events per second. Access audit events are not generated for each file read and write operation, but generated once per file metadata operation, such as when a user creates, opens, or deletes a file.

Topics

Audit event log destinations

When you enable file access auditing, you must configure an AWS service to which Amazon FSx sends the audit event logs. You can send audit event logs to either an Amazon CloudWatch Logs log stream in a CloudWatch Logs log group or an Amazon Data Firehose delivery stream. You choose the audit event logs destination either when you create your Amazon FSx for Windows File Server file system, or anytime after by updating an existing file system. For more information, see Managing file access auditing.

Following are some recommendations that may help you decide which audit event logs destination to choose:

  • Choose CloudWatch Logs if you want to store, view, and search audit event logs in the Amazon CloudWatch console, run queries on the logs using CloudWatch Logs Insights, and trigger CloudWatch alarms or Lambda functions.

  • Choose Firehose if you want to continuously stream events to storage in Amazon S3, to a database in Amazon Redshift, to Amazon OpenSearch Service, or to AWS Partner solutions (such as Splunk or Datadog) for further analysis.

By default, Amazon FSx will create and use a default CloudWatch Logs log group in your account as the audit event log destination. If you want to use a custom CloudWatch Logs log group or use Firehose as the audit event log destination, here are the requirements for the names and locations of the audit event log destination:

  • The name of the CloudWatch Logs log group must begin with the /aws/fsx/ prefix. If you don't have an existing CloudWatch Logs log group when you create or update a file system on the console, Amazon FSx can create and use a default log stream in the CloudWatch Logs /aws/fsx/windows log group. If you don't want to use the default log group, the configuration UI lets you create a CloudWatch Logs log group when you create or update your file system on the console.

  • The name of the Firehose delivery stream must begin with the aws-fsx- prefix. If you don't have an existing Firehose delivery stream, you can create one when you create or update your file system at the console.

  • The Firehose delivery stream must be configured to use Direct PUT as its source. You cannot use an existing Kinesis data stream as a data source for your delivery stream.

  • The destination (either CloudWatch Logs log group or Firehose delivery stream) must be in the same AWS partition, AWS Region, and AWS account as your Amazon FSx file system.

You can change the audit event log destination at any time (for example, from CloudWatch Logs to Firehose). When you do so, new audit event logs are sent only to the new destination.

Best effort audit event log delivery

Typically, audit event log records are delivered to the destination in minutes, but can sometimes take longer. On very rare occasions, audit event log records might be missed. If your use case requires particular semantics (for example, ensuring that no audit events are missed), we recommend that you account for missed events when designing your workflows. You can audit for missed events by scanning the file and folder structure on your file system.

Migrating your audit controls

If you have audit controls (SACLs) already set up on your existing file data, you can create an Amazon FSx file system and migrate your data to your new file system. We recommend using AWS DataSync to transfer data and the associated SACLs to your Amazon FSx file system. As an alternative solution, you can use Robocopy (Robust File Copy). For more information, see Migrating existing file storage to Amazon FSx.

Viewing event logs

You can view the audit event logs after Amazon FSx has started emitting them. Where and how you view the logs depends on the audit event log destination:

  • You can view CloudWatch Logs logs by going to the CloudWatch console and choosing the log group and log stream to which your audit event logs are sent. For more information, see View log data sent to CloudWatch Logs in the Amazon CloudWatch Logs User Guide.

    You can use CloudWatch Logs Insights to interactively search and analyze your log data. For more information, see Analyzing Log Data with CloudWatch Logs Insights, in the Amazon CloudWatch Logs User Guide.

    You can also export the audit event logs to Amazon S3. For more information, see Exporting Log Data to Amazon S3, also in the Amazon CloudWatch Logs User Guide.

  • You can't view the audit event logs on Firehose. However, you can configure Firehose to forward the logs to a destination that you can read from. The destinations include Amazon S3, Amazon Redshift, Amazon OpenSearch Service, and partner solutions such as Splunk and Datadog, For more information, see Choose destination in the Amazon Data Firehose Developer Guide.

Audit event fields

This section provides descriptions of the information in audit event logs and examples of audit events.

Following are descriptions of the salient fields in a Windows audit event.

  • EventID refers to the Microsoft-defined Windows event log event ID. See Microsoft documentation for information on file system events and file share events.

  • SubjectUserName refers to the user performing the access.

  • ObjectName refers to the target file, folder, or file share that was accessed.

  • ShareName is available for events that are generated for file share access. For example, EventID 5140 is generated when a network share object was accessed.

  • IpAddress refers to the client that initiated the event for file share events.

  • Keywords, when available, refer to whether the file access was successful or a failure. For successful accesses, the value is 0x8020000000000000. For failed accesses, the value is 0x8010000000000000.

  • TimeCreated SystemTime refers to the time the event was generated in the system and shown in <YYYY-MM-DDThh:mm:ss.s>Z format.

  • Computer refers to the DNS name of the file system Windows Remote PowerShell Endpoint and can be used to identify the file system.

  • AccessMask, when available, refers to the type of file access performed (for example, ReadData, WriteData).

  • AccessList refers to requested or granted access to an Object. For details, see the table below and Microsoft documentation (such as in Event 4556).

Access Type Access Mask Value

Read Data or List Directory

0x1

%%4416

Write Data or Add File

0x2

%%4417

Append Data or Add Subdirectory

0x4

%%4418

Read Extended Attributes

0x8

%%4419

Write Extended Attributes

0x10

%%4420

Execute/Traverse

0x20

%%4421

Delete Child

0x40

%%4422

Read Attributes

0x80

%%4423

Write Attributes

0x100

%%4424

Delete

0x10000

%%1537

Read ACL

0x20000

%%1538

Write ACL

0x40000

%%1539

Write Owner

0x80000

%%1540

Synchronize

0x100000

%%1541

Access Security ACL

0x1000000

%%1542

Following are some key events with examples. Note that the XML is formatted for readability.

Event ID 4660 is logged when an object is deleted.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4660</EventID><Version>0</Version><Level>0</Level>
<Task>12800</Task><Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords><TimeCreated SystemTime='2021-05-18T04:51:56.916563800Z'/>
<EventRecordID>315452</EventRecordID><Correlation/>
<Execution ProcessID='4' ThreadID='5636'/><Channel>Security</Channel>
<Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System><EventData>
<Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113</Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x50932f71</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='HandleId'>0x12e0</Data><Data Name='ProcessId'>0x4</Data><Data Name='ProcessName'></Data>
<Data Name='TransactionId'>{00000000-0000-0000-0000-000000000000}</Data></EventData></Event>

Event ID 4659 is logged on a request to delete a file.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4659</EventID><Version>0</Version><Level>0</Level><Task>12800</Task><Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords><TimeCreated SystemTime='2021-0603T19:18:09.951551200Z'/>
<EventRecordID>308888</EventRecordID><Correlation/><Execution ProcessID='4' ThreadID='5540'/>
<Channel>Security</Channel><Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System>
<EventData><Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113</Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2a9a603f</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='ObjectType'>File</Data><Data Name='ObjectName'>\Device\HarddiskVolume8\shar\event.txt</Data>
<Data Name='HandleId'>0x0</Data><Data Name='TransactionId'>{00000000-0000-0000-0000-000000000000}</Data>
<Data Name='AccessList'>%%1537
				%%4423
				</Data><Data Name='AccessMask'>0x10080</Data><Data Name='PrivilegeList'>-</Data>
<Data Name='ProcessId'>0x4</Data></EventData></Event>

Event ID 4663 is logged when a specific operation was performed on the object. The following example shows reading data from a file, which can be interpreted from AccessList %%4416.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4663< /EventID><Version>1</Version><Level>0</Level><Task>12800</Task><Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords><TimeCreated SystemTime='2021-06-03T19:10:13.887145400Z'/>
<EventRecordID>308831</EventRecordID><Correlation/><Execution ProcessID='4' ThreadID='6916'/>
<Channel>Security</Channel><Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System>
<EventData>< Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113< /Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2a9a603f</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='ObjectType'>File</Data><Data Name='ObjectName'>\Device\HarddiskVolume8\share\event.txt</Data>
<Data Name='HandleId'>0x101c</Data><Data Name='AccessList'>%%4416
				</Data>
<Data Name='AccessMask'>0x1</Data><Data Name='ProcessId'>0x4</Data>
<Data Name='ProcessName'></Data><Data Name='ResourceAttributes'>S:AI</Data>
</EventData></Event>

The following example shows write/append data from a file, which can be interpreted from AccessList %%4417.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4663</EventID><Version>1</Version><Level>0</Level><Task>12800</Task><Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords><TimeCreated SystemTime='2021-06-03T19:12:16.813827100Z'/>
<EventRecordID>308838</EventRecordID><Correlation/><Execution ProcessID='4' ThreadID='5828'/>
<Channel>Security</Channel><Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System>
<EventData><Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113</Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2a9a603f</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='ObjectType'>File</Data><Data Name='ObjectName'>\Device\HarddiskVolume8\share\event.txt</Data>
<Data Name='HandleId'>0xa38</Data><Data Name='AccessList'>%%4417
				</Data><Data Name='AccessMask'>0x2</Data><Data Name='ProcessId'>0x4</Data>
<Data Name='ProcessName'></Data><Data Name='ResourceAttributes'>S:AI</Data></EventData></Event>

Event ID 4656 indicates that a specific access was requested for an object. In the following example, the Read request was initiated to ObjectName "permtest" and was a failed attempt, as seen in the Keywords value of 0x8010000000000000.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4656</EventID><Version>1</Version><Level>0</Level><Task>12800</Task><Opcode>0</Opcode>
<Keywords>0x8010000000000000</Keywords><TimeCreated SystemTime='2021-06-03T19:22:55.113783500Z'/>
<EventRecordID>308919</EventRecordID><Correlation/><Execution ProcessID='4' ThreadID='4924'/>
<Channel>Security</Channel><Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System>
<EventData><Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113</Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2a9a603f</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='ObjectType'>File</Data><Data Name='ObjectName'>\Device\HarddiskVolume8\share\permtest</Data>
<Data Name='HandleId'>0x0</Data><Data Name='TransactionId'>{00000000-0000-0000-0000-000000000000}</Data>
<Data Name='AccessList'>%%1541
				%%4416
				%%4423
				</Data><Data Name='AccessReason'>%%1541:	%%1805
				%%4416:	%%1805
				%%4423:	%%1811	D:(A;OICI;0x1301bf;;;AU)
				</Data><Data Name='AccessMask'>0x100081</Data><Data Name='PrivilegeList'>-</Data>
<Data Name='RestrictedSidCount'>0</Data><Data Name='ProcessId'>0x4</Data><Data Name='ProcessName'></Data>
<Data Name='ResourceAttributes'>-</Data></EventData></Event>

Event ID 4670 is logged when permissions for an object are changed. The following example shows that user "admin" modified the permission on ObjectName "permtest" to add permissions to SID "S-1-5-21-658495921-4185342820-3824891517-1113". Refer to Microsoft documentation for more information on how to interpret the permissions.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>4670</EventID><Version>0</Version><Level>0</Level>
<Task>13570</Task><Opcode>0</Opcode><Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime='2021-06-03T19:39:47.537129500Z'/><EventRecordID>308992</EventRecordID>
<Correlation/><Execution ProcessID='4' ThreadID='2776'/><Channel>Security</Channel>
<Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System><EventData>
<Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-1113</Data>
<Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2a9a603f</Data><Data Name='ObjectServer'>Security</Data>
<Data Name='ObjectType'>File</Data><Data Name='ObjectName'>\Device\HarddiskVolume8\share\permtest</Data>
<Data Name='HandleId'>0xcc8</Data>
<Data Name='OldSd'>D:PAI(A;OICI;FA;;;SY)(A;OICI;FA;;;S-1-5-21-658495921-4185342820-3824891517-2622)</Data>
<Data Name='NewSd'>D:PARAI(A;OICI;FA;;;S-1-5-21-658495921-4185342820-3824891517-1113)(A;OICI;FA;;;SY)(A;OICI;FA;;;
S-1-5-21-658495921-4185342820-3824891517-2622)</Data><Data Name='ProcessId'>0x4</Data>
<Data Name='ProcessName'></Data></EventData></Event>

Event ID 5140 is logged every time a file share is accessed.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>5140</EventID><Version>1</Version><Level>0</Level><Task>12808</Task><Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords><TimeCreated SystemTime='2021-06-03T19:32:07.535208200Z'/>
<EventRecordID>308947</EventRecordID><Correlation/><Execution ProcessID='4' ThreadID='3120'/>
<Channel>Security</Channel><Computer>amznfsxgyzohmw8.example.com</Computer><Security/></System>
<EventData><Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-2620</Data>
<Data Name='SubjectUserName'>EC2AMAZ-1GP4HMN$</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x2d4ca529</Data><Data Name='ObjectType'>File</Data><Data Name='IpAddress'>172.45.6.789</Data>
<Data Name='IpPort'>49730</Data><Data Name='ShareName'>\\AMZNFSXCYDKLDZZ\share</Data>
<Data Name='ShareLocalPath'>\??\D:\share</Data><Data Name='AccessMask'>0x1</Data><Data Name='AccessList'>%%4416
				</Data></EventData></Event>

Event ID 5145 is logged when access is denied at the file share level. The following example shows access to ShareName "demoshare01" was denied.

<Event xmlns='http://schemas.microsoft.com/win/2004/08/events/event'><System>
<Provider Name='Microsoft-Windows-Security-Auditing' Guid='{54849625-5478-4994-A5BA-3E3B0328C30D}'/>
<EventID>5145</EventID><Version>0</Version><Level>0</Level>
<Task>12811</Task><Opcode>0</Opcode><Keywords>0x8010000000000000</Keywords>
<TimeCreated SystemTime='2021-05-19T22:30:40.485188700Z'/><EventRecordID>282939</EventRecordID>
<Correlation/><Execution ProcessID='4' ThreadID='344'/><Channel>Security</Channel>
<Computer>amznfsxtmn9autz.example.com</Computer><Security/></System><EventData>
<Data Name='SubjectUserSid'>S-1-5-21-658495921-4185342820-3824891517-
1113</Data><Data Name='SubjectUserName'>Admin</Data><Data Name='SubjectDomainName'>example</Data>
<Data Name='SubjectLogonId'>0x95b3fb7</Data><Data Name='ObjectType'>File</Data>
<Data Name='IpAddress'>172.31.7.112</Data><Data Name='IpPort'>59979</Data>
<Data Name='ShareName'>\\AMZNFSXDPNTE0DC\demoshare01</Data><Data Name='ShareLocalPath'>\??\D:\demoshare01</Data>
<Data Name='RelativeTargetName'>Desktop.ini</Data><Data Name='AccessMask'>0x120089</Data>
<Data Name='AccessList'>%%1538 %%1541 %%4416 %%4419 %%4423 </Data><Data Name='AccessReason'>%%1538:
%%1804 %%1541: %%1805 %%4416: %%1805 %%4419: %%1805 %%4423: %%1805 </Data></EventData></Event>

If you use CloudWatch Logs Insights to search your log data, you can run queries on the event fields, as shown by the following examples:

  • To query for a specific event ID:

    fields @message
   | filter @message like /4660/

  • To query all events matching a particular file name:

    fields @message
   | filter @message like /event.txt/

For more information on the CloudWatch Logs Insights query language, see Analyzing Log Data with CloudWatch Logs Insights, in the Amazon CloudWatch Logs User Guide.