CVE-2018-16857
Description
It was found that the 'bad password observation window' was ineffective when set to a value greater than 3 minutes. This could allow for brute force password attacks in some situations.
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
Bad password lockout is not configured by default, it is only
effective if a threshold has been set with (eg):
samba-tool domain passwordsettings set --account-lockout-threshold=3
To mitigate the issue set a shorter 'Reset account lockout after'
window (the ineffective default is 30, anything less than 15 will
work):
samba-tool domain passwordsettings set --reset-account-lockout-after=15
NOTE: If a fine-grained password policy (PSO) is set, this must also
be done on each PSO.
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 | 7.4 | 5.9 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Acknowledgements
Red Hat would like to thank the Samba project for reporting this issue. Upstream acknowledges Isaac Boukris as the original reporter.
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