Vulnerabilities
Misconfiguration
Runtime Security
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CVE Vulnerabilities

CVE-2019-14870

Improper Authorization

Published: Dec 10, 2019 | Modified: Nov 21, 2024
CVSS 3.x
5.4
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CVSS 2.x
6.4 MEDIUM
AV:N/AC:L/Au:N/C:P/I:P/A:N
RedHat/V2
RedHat/V3
5.4 MODERATE
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Ubuntu
MEDIUM
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2019-14870
CWEhttps://cwe.mitre.org/data/definitions/285.html

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 S4U (MS-SFU) Kerberos delegation model includes a feature allowing for a subset of clients to be opted out of constrained delegation in any way, either S4U2Self or regular Kerberos authentication, by forcing all tickets for these clients to be non-forwardable. In AD this is implemented by a user attribute delegation_not_allowed (aka not-delegated), which translates to disallow-forwardable. However the Samba AD DC does not do that for S4U2Self and does set the forwardable flag even if the impersonated client has the not-delegated flag set.

Weakness

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.

Affected Software

Name Vendor Start Version End Version
Samba Samba 4.0.0 (including) 4.9.17 (excluding)
Samba Samba 4.10.0 (including) 4.10.11 (excluding)
Samba Samba 4.11.0 (including) 4.11.3 (excluding)
Samba Ubuntu bionic *
Samba Ubuntu devel *
Samba Ubuntu disco *
Samba Ubuntu eoan *
Samba Ubuntu trusty *
Samba Ubuntu trusty/esm *
Samba Ubuntu upstream *
Samba Ubuntu xenial *

Extended Description

Assuming a user with a given identity, authorization is the process of determining whether that user can access a given resource, based on the user’s privileges and any permissions or other access-control specifications that apply to the resource. When access control checks are not applied consistently - or not at all - users are able to access data or perform actions that they should not be allowed to perform. This can lead to a wide range of problems, including information exposures, denial of service, and arbitrary code execution.

Potential Mitigations

  • Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
  • Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
  • For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
  • For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
  • One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.

References

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