After Junos OS upgrade from 15.1X49 to 17.x or higher, IDP attack database version is N/A.
root@jtac-srx> show security idp security-package-version Jun 23 05:13:48 Attack database version:N/A(N/A) Detector version :12.6.160200109 Policy template version :N/A
This is expected behavior as there is a change in the back end database (from BDB to SQLite ) from Junos 17.x and higher release.
After the upgrade mentioned above, do a full-update of the security package using 'request security idp security-package download full-update' followed by 'request security idp security-package install'
'request security idp security-package download full-update'
'request security idp security-package install'
This will update the secdb back end to the SQLite3 format.