/usr/share/perl5/EBox/Squid/Model/ is in zentyal-squid 2.3.11+quantal1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/perl5/EBox/Squid/Model/AccessRules.pm
/usr/share/perl5/EBox/Squid/Model/AntiVirus.pm
/usr/share/perl5/EBox/Squid/Model/CategorizedLists.pm
/usr/share/perl5/EBox/Squid/Model/ContentFilterThreshold.pm
/usr/share/perl5/EBox/Squid/Model/DelayPools.pm
/usr/share/perl5/EBox/Squid/Model/DomainFilter.pm
/usr/share/perl5/EBox/Squid/Model/DomainFilterCategories.pm
/usr/share/perl5/EBox/Squid/Model/DomainFilterSettings.pm
/usr/share/perl5/EBox/Squid/Model/Extensions.pm
/usr/share/perl5/EBox/Squid/Model/FilterProfiles.pm
/usr/share/perl5/EBox/Squid/Model/GeneralSettings.pm
/usr/share/perl5/EBox/Squid/Model/MIME.pm
/usr/share/perl5/EBox/Squid/Model/NoCacheDomains.pm
/usr/share/perl5/EBox/Squid/Model/RequestsGraph.pm
/usr/share/perl5/EBox/Squid/Model/TrafficDetails.pm
/usr/share/perl5/EBox/Squid/Model/TrafficReportOptions.pm
/usr/share/perl5/EBox/Squid/Model/TrafficSizeGraph.pm
/usr/share/perl5/EBox/Squid/Model/TransparentExceptions.pm