Samba 4.4.x < 4.4.15 / 4.5.x < 4.5.12 / 4.6.x < 4.6.6 KDC-REP Service Name Validation (Orpheus' Lyre)
Medium Nessus Plugin ID 101773
SynopsisThe remote Samba server is affected by a service impersonation vulnerability.
DescriptionThe version of Samba running on the remote host is 4.4.x prior to 4.4.15, 4.5.x prior to 4.5.12, or 4.6.x prior to 4.6.6. It is, therefore, affected by a logic flaw in the Heimdal implementation of Kerberos, specifically within the _krb5_extract_ticket() function within lib/krb5/ticket.c, due to the unsafe use of cleartext metadata from an unauthenticated ticket instead of the encrypted version stored in the Key Distribution Center (KDC) response. A man-in-the-middle attacker can exploit this issue to impersonate Kerberos services. This can potentially result in a privilege escalation or the theft of credentials. Note that Samba versions built against MIT Kerberos are not impacted by this issue.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
SolutionUpgrade to Samba version 4.4.15 / 4.5.12 / 4.6.6 or later.
Alternatively, if you are not running Samba as an Active Directory domain controller, as a workaround, you can rebuild Samba using the following command : ./configure --with-system-mitkrb5.