CVE-2019-14861

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.

Weakness

During installation, installed file permissions are set to allow anyone to modify those files.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/1.html
• https://cwe.mitre.org/data/definitions/127.html
• https://cwe.mitre.org/data/definitions/81.html

References

• http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00038.html
• http://www.openwall.com/lists/oss-security/2024/06/24/3
• https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-14861
• https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PJH3ROOFYMOATD2UEPC47P5RPBDTY77E/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WNKA4YIPV7AZR7KK3GW6L3HKGHSGJZFE/
• https://security.gentoo.org/glsa/202003-52
• https://security.netapp.com/advisory/ntap-20191210-0002/
• https://usn.ubuntu.com/4217-1/
• https://usn.ubuntu.com/4217-2/
• https://www.samba.org/samba/security/CVE-2019-14861.html
• https://www.synology.com/security/advisory/Synology_SA_19_40