Considerations for configuration

First execution

If no only_logs_after value is provided, the module will only fetch the logs of the date of the execution.

Filtering

If the S3 bucket contains a long history of logs and its directory structure is organized by dates, it's possible to filter which logs will be read by Wazuh. There are multiple configuration options to do so:

  • only_logs_after: Allows filtering logs produced after a given date. The date format must be YYYY-MMM-DD, for example, 2018-AUG-21 would filter logs produced after the 21st of August 2018 (that day included).

  • aws_account_id: This option will only work on CloudTrail, VPC, and Config buckets. If you have logs from multiple accounts, you can filter which ones will be read by Wazuh. You can specify multiple ids separating them by commas.

  • regions: This option will only work on CloudTrail, VPC and Config buckets, and Inspector service. If you have logs from multiple regions, you can filter which ones will be read by Wazuh. You can specify multiple regions separating them by commas. It is mandatory to specify the region when configuring an S3 bucket from an AWS GovCloud region (available GovCloud regions are us-gov-east-1 and us-gov-west-1).

  • path: If you have your logs stored in a given path, it can be specified using this option. For example, to read logs stored in directory vpclogs/ the path vpclogs need to be specified. It can also be specified with / or \.

  • aws_organization_id: This option will only work on CloudTrail buckets. If you have configured an organization, you need to specify the name of the AWS organization by using this parameter.

Older logs

The aws-s3 Wazuh module only looks for new logs in buckets based on the key of the last processed log object, which includes the datetime stamp. If older logs are loaded into the S3 bucket or the only_logs_after option date is set to a datetime earlier than previous executions of the module, the older log files will be ignored and not ingested into Wazuh.

On the other hand, the CloudWatch Logs module can process logs older than the first one processed. To do so, specify an older only_logs_after value, and the module will process all logs between the value set for only_logs_after and the first log executed without generating duplicate alerts.

Reparse

Note

Option not available for CloudWatch Logs.

Warning

Using the reparse option will fetch and process every log from the starting date until the present. This process may generate duplicate alerts.

To process older logs, it's necessary to manually execute the module using the --reparse or -o option. Executing the module with this option will use the only_logs_after value provided to fetch and process every log from that date until the present. If no only_logs_after value was provided, it will use the date of the first file processed.

Below there is an example of a manual execution of the module using the --reparse option on a manager, being /var/ossec the Wazuh installation path:

# cd /var/ossec/wodles/aws
# ./aws-s3 -b 'wazuh-example-bucket' --reparse --only_logs_after '2021-Jun-10' --debug 2

The --debug 2 parameter was used to get a verbose output since by default the script won't print anything on the terminal, and it could seem like it's not working when it could be handling a great amount of data instead.

Connection configuration for retries

Some calls to AWS services may fail when made in highly congested environments. The AWS pip dependencies client raises ClientError exceptions describing the errors. This kind of exception often needs repeating the call, without further handling. To help retry these calls, Boto3 provides Retries. This feature allows retrying client calls to AWS services when errors like ThrottlingException are experienced.

Users can customize two retry configurations.

  • retry_mode: legacy, standard, and adaptive.

    • Legacy mode is the default retry mode. It sets the older version 1 for the retry handler. This includes:

      • Retry attempts for a limited number of errors/exceptions.

      • A default value of 5 for maximum call attempts.

    • Standard mode sets the updated version 2 for the retry handler. It includes:

      • Extended functionality over that found in the legacy mode where retry attempts apply to an expanded list of errors/exceptions.

      • A default value of 3 for maximum call attempts.

    • Adaptive mode is an experimental retry mode. It includes all the features of the standard mode. This mode offers flexibility in client-side retries. Retries adapt to the error/exception state response from an AWS service.

  • max_attempts: The maximum number of attempts including the initial call. This configuration can override the default value set by the retry mode.

You can specify the retry configuration in the ~/.aws/config configuration file. The profile section must include the max_attempts, retry_mode, and region settings. It is important to use the same profile as the one you chose as your authentication method. If the authentication method doesn't have a profile, then the [Default] profile must include the configurations. In case the system doesn't have this file, the aws-s3 Wazuh module defines the following values by default:

  • retry_mode=standard

  • max_attempts=10.

The following example of a ~/.aws/config file sets retry parameters for the dev profile:

[profile dev]
region=us-east-1
max_attempts=5
retry_mode=standard

Configuring multiple services

Below there is an example of different services configuration:

<wodle name="aws-s3">
  <disabled>no</disabled>
  <interval>10m</interval>
  <run_on_start>yes</run_on_start>
  <skip_on_error>yes</skip_on_error>

  <!-- Inspector, two regions, and logs after January 2018 -->
  <service type="inspector">
    <aws_profile>default</aws_profile>
    <regions>us-east-1,us-east-2</regions>
    <only_logs_after>2018-JAN-01</only_logs_after>
  </service>

  <!-- GuardDuty, 'production' profile -->
  <bucket type="guardduty">
    <name>wazuh-aws-wodle</name>
    <path>guardduty</path>
    <aws_profile>production</aws_profile>
  </bucket>

  <!-- Config, 'default' profile -->
  <bucket type="config">
    <name>wazuh-aws-wodle</name>
    <path>config</path>
    <aws_profile>default</aws_profile>
  </bucket>

  <!-- KMS, 'dev' profile -->
  <bucket type="custom">
    <name>wazuh-aws-wodle</name>
    <path>kms_compress_encrypted</path>
    <aws_profile>dev</aws_profile>
  </bucket>

  <!-- CloudTrail, 'default' profile, without 'path' tag -->
  <bucket type="cloudtrail">
    <name>wazuh-cloudtrail</name>
    <aws_profile>default</aws_profile>
  </bucket>

  <!-- CloudTrail, 'gov1' profile, and 'us-gov-east-1' GovCloud region -->
  <bucket type="cloudtrail">
    <name>wazuh-aws-wodle</name>
    <path>cloudtrail-govcloud</path>
    <regions>us-gov-east-1</regions>
    <aws_profile>gov1</aws_profile>
  </bucket>

  <!-- CloudTrail, 'gov2' profile, and 'us-gov-west-1' GovCloud region -->
  <bucket type="cloudtrail">
    <name>wazuh-aws-wodle</name>
    <path>cloudtrail-govcloud</path>
    <regions>us-gov-west-1</regions>
    <aws_profile>gov2</aws_profile>
  </bucket>

</wodle>

Using non-default AWS endpoints

VPC endpoints

VPC endpoints can help reduce the traffic cost in your VPC by allowing connections from the VPC to the AWS services that support it, without having to rely on their public IP to connect to the AWS Services. As the aws-s3 Wazuh module connects to the AWS S3 service to access the data from the S3 buckets, regardless of the service they come from, VPC endpoints can be used, as long as Wazuh runs in the VPC. The same applies to the AWS services the aws-s3 Wazuh module supports, such as CloudWatchLogs, provided that they are compatible with VPC endpoints. The list of AWS services supporting VPC endpoints can be checked here.

The service_endpoint and sts_endpoint tags can be used to specify the VPC endpoint URL for obtaining the data and for logging into STS when an IAM role was specified, respectively. Here is an example of a valid configuration:

<wodle name="aws-s3">
  <disabled>no</disabled>
  <interval>10m</interval>
  <run_on_start>yes</run_on_start>
  <skip_on_error>yes</skip_on_error>

  <bucket type="cloudtrail">
    <name>wazuh-cloudtrail</name>
    <aws_profile>default</aws_profile>
    <service_endpoint>https://bucket.xxxxxx.s3.us-east-2.vpce.amazonaws.com</service_endpoint>
  </bucket>

  <bucket type="cloudtrail">
    <name>wazuh-cloudtrail-2</name>
    <aws_profile>default</aws_profile>
    <iam_role_arn>arn:aws:iam::xxxxxxxxxxx:role/wazuh-role</iam_role_arn>
    <sts_endpoint>xxxxxx.sts.us-east-2.vpce.amazonaws.com</sts_endpoint>
    <service_endpoint>https://bucket.xxxxxx.s3.us-east-2.vpce.amazonaws.com</service_endpoint>
  </bucket>

  <service type="cloudwatchlogs">
    <aws_profile>default</aws_profile>
    <regions>us-east-2</regions>
    <aws_log_groups>log_group_name</aws_log_groups>
    <service_endpoint>https://xxxxxx.logs.us-east-2.vpce.amazonaws.com</service_endpoint>
  </service>

</wodle>

FIPS endpoints

Wazuh supports the use of AWS FIPS endpoints to comply with the Federal Information Processing Standard (FIPS) Publication 140-2. Depending on the service and region of choice, a different endpoint must be selected from the AWS FIPS endpoints list. Specify the selected endpoint in the ossec.conf file using the service_endpoint tag.

The following is an example of a valid configuration.

<wodle name="aws-s3">
  <disabled>no</disabled>
  <interval>10m</interval>
  <run_on_start>yes</run_on_start>
  <skip_on_error>yes</skip_on_error>

  <service type="cloudwatchlogs">
    <aws_profile>default</aws_profile>
    <regions>us-east-2</regions>
    <aws_log_groups>log_group_name</aws_log_groups>
    <service_endpoint>logs-fips.us-east-2.amazonaws.com</service_endpoint>
  </service>

</wodle>