Hi Qasim,
I guess the alerts you're receiving are like this one:
** Alert 1609954424.11479: - ossec,rootcheck,gdpr_IV_35.7.d,
2021 Jan 06 18:33:44 groovy->rootcheck
Rule: 510 (level 7) -> 'Host-based anomaly detection event (rootcheck).'
NTFS Alternate data stream found: 'C:\some-file'. Possible hidden content.
title: NTFS Alternate data stream found: 'C:\some-file'.
Alerts from the rootkit detector (Rootcheck) have rule ID 510. Their message is in a field called "title". So we need to create a rule with parent 510 and matching the beginning of the message, then we set the level of that rule to 0, meaning that it should not produce an alert.
Copy this rule into /var/ossec/etc/rules/local_rules.xml, or any other file in the same directory:
<group name="ossec,local">
<rule id="100510" level="0">
<if_sid>510</if_sid>
<field name="title">^NTFS Alternate data stream found</field>
<description>NTFS alternate data stream found.</description>
<group>rootcheck,gdpr_IV_35.7.d,</group>
</rule>
</group>
Then, restart your manager. These alerts should not appear any more!
Hope it helps.