/etc/mediawiki/ is in mediawiki 1:1.19.20+dfsg-0+deb7u3.
This file is owned by root:root, with mode 0o755.
..
/etc/mediawiki-extensions/extensions-available/
/etc/mediawiki-extensions/extensions-available/Asirra.php
/etc/mediawiki-extensions/extensions-available/ConfirmEdit.php
/etc/mediawiki-extensions/extensions-available/FancyCaptcha.php
/etc/mediawiki-extensions/extensions-available/Gadgets.php
/etc/mediawiki-extensions/extensions-available/MathCaptcha.php
/etc/mediawiki-extensions/extensions-available/Nuke.php
/etc/mediawiki-extensions/extensions-available/ParserFunctions.php
/etc/mediawiki-extensions/extensions-available/QuestyCaptcha.php
/etc/mediawiki-extensions/extensions-available/ReCaptcha.php
/etc/mediawiki-extensions/extensions-available/Renameuser.php
/etc/mediawiki-extensions/extensions-available/Vector.php
/etc/mediawiki-extensions/extensions-available/WikiEditor.php
/etc/mediawiki/apache.conf
/etc/mediawiki/cherokee.conf