Versions Affected : All versions prior to FreeNAS 11.2-U8


Description

An authenticated user can crash the DCE/RPC DNS management server by creating records matching the zone name in different case spelling.

All Samba versions 4.x.x before 4.9.17, 4.10.x before 4.10.11 and 4.11.x before 4.11.3 have an issue, where the (poorly named) dnsserver RPC pipe provides administrative facilities to modify DNS records and zones. Samba, when acting as an AD DC, stores DNS records in LDAP. In AD, the default permissions on the DNS partition allow creation of new records by authenticated users. This is used for example to allow machines to self-register in DNS. If a DNS record was created that case-insensitively matched the name of the zone, the ldb_qsort() and dns_name_compare() routines could be confused into reading memory prior to the list of DNS entries when responding to DnssrvEnumRecords() or DnssrvEnumRecords2() and so following invalid memory as a pointer.

Workaround

No workaround is available.


Mitigation

  • Upgrade to FreeNAS 11.2-U8 or later

Commit

Further information