/usr/share/mozilla/extensions/ is in xul-ext-noscript 2.6.8.19-1~deb7u2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/mozilla/extensions/dlm@emusic.com/
/usr/share/mozilla/extensions/dlm@emusic.com/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/songbird@songbirdnest.com/
/usr/share/mozilla/extensions/songbird@songbirdnest.com/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/toolkit@mozilla.org/
/usr/share/mozilla/extensions/toolkit@mozilla.org/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}/
/usr/share/mozilla/extensions/{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/{a23983c0-fd0e-11dc-95ff-0800200c9a66}/
/usr/share/mozilla/extensions/{a23983c0-fd0e-11dc-95ff-0800200c9a66}/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/{a463f10c-3994-11da-9945-000d60ca027b}/
/usr/share/mozilla/extensions/{a463f10c-3994-11da-9945-000d60ca027b}/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/{aa5ca914-c309-495d-91cf-3141bbb04115}/
/usr/share/mozilla/extensions/{aa5ca914-c309-495d-91cf-3141bbb04115}/{73a6fe31-595d-460b-a920-fcc0f8843232}
/usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/
/usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/{73a6fe31-595d-460b-a920-fcc0f8843232}