Malware founded in plugin’s folder

Good day! We did a malware scan using Malcare plugin and we found the following malware:

paths:

Infected File (./wp-content/webp-express/htaccess-capability-tests/module-loaded/headers/server-signature/test.php)
Infected File (./wp-content/webp-express/htaccess-capability-tests/server-signature/on/test.php)
Infected File (./wp-content/webp-express/htaccess-capability-tests/server-signature/off/test.php)

The code in these files is:
<?php if (isset($_SERVER['SERVER_SIGNATURE']) && ($_SERVER['SERVER_SIGNATURE'] != '')) { echo 0; } else { echo 1; }

Is it a malware or just normal files?