Hello Andy,
We've had other tickets/requests like yours too. The CVE-2017-9079 dropbear issue is fixed in ZD 10.0+, but unfortunately ZD1100 last supported release is 9.10.x, and changes will not be back-ported.
Other customers had to upgrade to ZD1200 model controllers if this is your concern. The security team reports this is concidered a minor vulnerability, with a CVSS score of 4.7, and exploitability score of 1.0.