ReleaseJob#unpack builds job_dir = File.join(@release_dir, 'jobs', name) and job_tgz = File.join(@release_dir, 'jobs', "#{name}.tgz") where name returns @job_meta['name'], a value taken verbatim from the jobs: array of the attacker-supplied release.MF inside the uploaded tarball. These paths are then interpolated into a shell string: Bosh::Common::Exec.sh("tar -C #{job_dir} -xf #{job_tgz} 2>&1", :on_error => :return). Bosh::Common::Exec.sh executes via %x{#{command}} (bosh-common/lib/bosh/common/exec.rb:53), i.e. /bin/sh -c, so any shell metacharacters in name are interpreted. FileUtils.mkdir_p(job_dir) on line 49 creates the literal directory (no shell) and succeeds even when the name contains $()/;, so execution reaches the sh call.
Affected versions:
- BOSH Director: all versions prior to v282.1.12 (inclusive); fixed in v282.1.12 or later