Headline
CVE-2022-4563: Apply 2.5.1 fixes to develop by legoktm · Pull Request #6704 · freedomofpress/securedrop
A vulnerability was found in Freedom of the Press SecureDrop. It has been rated as critical. Affected by this issue is some unknown functionality of the file gpg-agent.conf. The manipulation leads to symlink following. Local access is required to approach this attack. The name of the patch is b0526a06f8ca713cce74b63e00d3730618d89691. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-215972.
/var/www/securedrop is now root-owned but world readable. This ensures that code can only be added/modified/removed by root, not www-data.
The package already installs files /var/www/securedrop with the correct permissions, we were just clobbering it in the postinst, which is now removed. We have an explicit chmod to adjust directory permissions.
We need special handling for config.py since it is installed by ansible instead of the package. Since it contains secrets, we want it to be only-readable by root/www-data and no one else.
The custom_logo.png is writable by www-data so administrators can change the logo from the web interface. In the future this could be moved somewhere else. The file may not exist yet (fresh installs), so we create it if necessary.
testinfra checks have been updated with the new permissions and took the time to de-duplicate the list of app directories in 7 different yaml files.
An attacker with access to www-data could have gpg-agent.conf be a symlink to a root-owned file (e.g. /etc/passwd) and trick the postinst into clobbering that file as root. Because the content is fixed, it’s pretty low risk but straightforward to fix.
* Add a postinst snippet to migrate the root crontab over to www-data on upgrade. * Modify ansible task to install cron jobs for www-data on new installs * Update testinfra checks to look at the www-data cron for the tmp cleaning job and verify that root’s crontab is empty.
There’s no need for us to run this as root, all the files alembic needs to touch (primarily the SQLite database) are writable by www-data. We specifically run the backup copying and deletion steps as www-data too so symlink attacks can’t be used to have root clobber other files.
For `mod_wsgi-express module-config`, we ship the generated file in the package itself. In a future (non-hotfix) release we will generate the file at build-time instead of hardcoding it.