/usr/share/mozilla/extensions/{8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4}/{e4a8a97b-f2ed-450b-b12d-ee082ba24781} is in xul-ext-greasemonkey 3.8-1~deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/mozilla/extensions/{8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4}/../../../xul-ext/greasemonkey