CVE-2019-14861
Description
From CVE.org
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.
Statement
This flaw does not affect the version of samba shipped with Red Hat Enterprise Linux because there is no support for samba as Active Directory Domain Controller.
Mitigation
The dnsserver task can be stopped by setting
'dcerpc endpoint servers = -dnsserver'in the smb.conf and restarting Samba.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality,Integrity
Technical Impact: Read Application Data; Modify Application Data
Acknowledgements
Red Hat would like to thank the Samba project for reporting this issue. Upstream acknowledges Andreas Oster as the original reporter.
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