/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/ is in chromium-ublock-origin 1.13.8+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/easylist-downloads.adblockplus.org//
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/easylist-downloads.adblockplus.org/easylist.txt
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/easylist-downloads.adblockplus.org/easyprivacy.txt
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/publicsuffix.org/
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/publicsuffix.org/list/
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/publicsuffix.org/list/effective_tld_names.dat
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/www.malwaredomainlist.com/
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/www.malwaredomainlist.com/hostslist//
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/www.malwaredomainlist.com/hostslist/README.md
/usr/share/chromium/extensions/ublock-origin/assets/thirdparties/www.malwaredomainlist.com/hostslist/hosts.txt