CVE-2020-17049 : Exploit Details and Defense Strategies
Learn about CVE-2020-17049, a security feature bypass vulnerability affecting various Microsoft Windows Server versions. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
A security feature bypass vulnerability in Kerberos KDC affects various Microsoft Windows Server versions.
Understanding CVE-2020-17049
What is CVE-2020-17049?
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 configured to use KCD could tamper with a service ticket to force the KDC to accept it.
The Impact of CVE-2020-17049
The vulnerability allows for unauthorized access and potential misuse of service tickets, compromising the security of affected systems.
Technical Details of CVE-2020-17049
Vulnerability Description
The update addresses the vulnerability by changing how the KDC validates service tickets used with KCD.
Affected Systems and Versions
- Windows Server 2019
- Windows Server 2019 (Server Core installation)
- Windows Server, version 1909 (Server Core installation)
- Windows Server, version 1903 (Server Core installation)
- Windows Server version 2004
- Windows Server 2016
- Windows Server 2016 (Server Core installation)
- Windows Server 2008 Service Pack 2
- Windows Server 2008 Service Pack 2 (Server Core installation)
- Windows Server 2008 Service Pack 2
- Windows Server 2008 R2 Service Pack 1
- Windows Server 2008 R2 Service Pack 1 (Server Core installation)
- Windows Server 2012
- Windows Server 2012 (Server Core installation)
- Windows Server 2012 R2
- Windows Server 2012 R2 (Server Core installation)
- Windows Server version 20H2
Exploitation Mechanism
The vulnerability can be exploited by compromising a service configured to use KCD to tamper with service tickets.
Mitigation and Prevention
Immediate Steps to Take
- Apply the security update provided by Microsoft to address the vulnerability.
- Monitor for any unauthorized access or unusual activities on the affected systems.
Long-Term Security Practices
- Regularly update and patch systems to prevent security vulnerabilities.
- Implement strong access controls and monitoring mechanisms to detect and respond to unauthorized access attempts.
Patching and Updates
Ensure that all affected systems are updated with the latest security patches to mitigate the risk of exploitation.