Synology-SA-18:60 Samba AD DC

Publish Time: 2018-11-28 18:34:16 UTC+8

Last Updated: 2019-12-17 16:18:37 UTC+8

Severity
Moderate
Status
Resolved

Abstract

CVE-2018-16841 and CVE-2018-16851 allow remote authenticated users to conduct denial-of-service attacks via a susceptible version of Synology Active Directory Server.

None of Synology products are affected by CVE-2018-14629, CVE-2018-16852, CVE-2018-16853, and CVE-2018-16857 as these vulnerabilities only affect Samba 4.9.0 and later.

Affected Products

Product Severity Fixed Release Availability
Active Directory Server Moderate Upgrade to 6.2.2-24922 or above.

Mitigation

None

Detail

  • CVE-2018-14629

    • Severity: Not affected
    • CVSS3 Base Score: 0.0
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:N
    • A denial of service vulnerability was discovered in Samba's LDAP server before versions 4.7.12, 4.8.7, and 4.9.3. A CNAME loop could lead to infinite recursion in the server. An unprivileged local attacker could create such an entry, leading to denial of service.

  • CVE-2018-16841

    • Severity: Moderate
    • CVSS3 Base Score: 6.5
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
    • Samba from version 4.3.0 and before versions 4.7.12, 4.8.7 and 4.9.3 are vulnerable to a denial of service. When configured to accept smart-card authentication, Samba's KDC will call talloc_free() twice on the same memory if the principal in a validly signed certificate does not match the principal in the AS-REQ. This is only possible after authentication with a trusted certificate. talloc is robust against further corruption from a double-free with talloc_free() and directly calls abort(), terminating the KDC process.

  • CVE-2018-16851

    • Severity: Moderate
    • CVSS3 Base Score: 5.3
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
    • Samba from version 4.0.0 and before versions 4.7.12, 4.8.7, 4.9.3 is vulnerable to a denial of service. During the processing of an LDAP search before Samba's AD DC returns the LDAP entries to the client, the entries are cached in a single memory object with a maximum size of 256MB. When this size is reached, the Samba process providing the LDAP service will follow the NULL pointer, terminating the process. There is no further vulnerability associated with this issue, merely a denial of service.

  • CVE-2018-16852

    • Severity: Not affected
    • CVSS3 Base Score: 0.0
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
    • Samba from version 4.9.0 and before version 4.9.3 is vulnerable to a NULL pointer de-reference. During the processing of an DNS zone in the DNS management DCE/RPC server, the internal DNS server or the Samba DLZ plugin for BIND9, if the DSPROPERTY_ZONE_MASTER_SERVERS property or DSPROPERTY_ZONE_SCAVENGING_SERVERS property is set, the server will follow a NULL pointer and terminate. There is no further vulnerability associated with this issue, merely a denial of service.

  • CVE-2018-16853

    • Severity: Not affected
    • CVSS3 Base Score: 0.0
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
    • Samba from version 4.7.0 has a vulnerability that allows a user in a Samba AD domain to crash the KDC when Samba is built in the non-default MIT Kerberos configuration. With this advisory the Samba Team clarify that the MIT Kerberos build of the Samba AD DC is considered experimental. Therefore the Samba Team will not issue security patches for this configuration. Additionally, Samba 4.7.12, 4.8.7 and 4.9.3 have been issued as security releases to prevent building of the AD DC with MIT Kerberos unless --with-experimental-mit-ad-dc is specified to the configure command.

  • CVE-2018-16857

    • Severity: Not affected
    • CVSS3 Base Score: 0.0
    • CVSS3 Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
    • Samba from version 4.9.0 and before version 4.9.3 that have AD DC configurations watching for bad passwords (to restrict brute forcing of passwords) in a window of more than 3 minutes may not watch for bad passwords at all. The primary risk from this issue is with regards to domains that have been upgraded from Samba 4.8 and earlier. In these cases the manual testing done to confirm an organisation's password policies apply as expected may not have been re-done after the upgrade.

Reference

Revision

Revision Date Description
1 2018-11-28 Initial public release.
2 2019-12-17 - Disclosed vulnerability details.
- Update for Active Directory Server is now available in Affected Products.