Are "" libraries in Piwik safe/authentic?

Hi. Are these legitimate entries by Piwik?

1-{REX}PHP.hexencoded.longstring.1: /home/excelle2/public_html/
2-{REX}PHP.hexencoded.longstring.1: /home/excelle2/public_html/
3-{REX}PHP.hexencoded.longstring.1: /home/excelle2/public_html/
4-{REX}PHP.hexencoded.longstring.1: /home/excelle2/public_html/
5-{REX}PHP.hexencoded.longstring.1: /home/excelle2/public_html/

I wasn’t able to find anything about it when searching the support site, generally online, nor on the forum, about the above. My security scanner marked these five things as malware; just wondering if it’s a false positive?

If not, what is it used for, please?

Thank you.