Unknown
CVE-2020-17049
CVE-2020-17049
Description
A security feature bypass vulnerability exists in the way Key Distribution Center (KDC) determines if a service ticket can be used for delegation via Kerberos Constrained Delegation (KCD).
To exploit the vulnerability, a compromised service that is configured to use KCD could tamper with a service ticket that is not valid for delegation to force the KDC to accept it.
The update addresses this vulnerability by changing how the KDC validates service tickets used with KCD.
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Technical Analysis
Technical analysis and exploit of the vulnerability are now publicly available:
https://blog.netspi.com/cve-2020-17049-kerberos-bronze-bit-overview/
https://blog.netspi.com/cve-2020-17049-kerberos-bronze-bit-theory/
https://blog.netspi.com/cve-2020-17049-kerberos-bronze-bit-attack/
Technical Analysis
Based on https://twitter.com/jakekarnes42/status/1329825159247642624
“The vulnerability impacts constrained delegation, which could be present in a single domain/forest. “
Note that the patch itself requires registry keys to be entered. Merely installing updates does not appear to protect the domain. There are issues introduced by this patch with Citrix and Federated Authentication service. (source https://twitter.com/mrgrayaz/status/1328517824633978912)
CVSS V3 Severity and Metrics
General Information
Vendors
- microsoft,
- samba
Products
- samba,
- windows server 2012,
- windows server 2012 r2,
- windows server 2016 -,
- windows server 2016 1903,
- windows server 2016 1909,
- windows server 2016 2004,
- windows server 2016 20h2,
- windows server 2019 -
References
