CVE-2020-8200 in Storefront Server
Summary
by MITRE
Improper authentication in Citrix StoreFront Server < 1912.0.1000 allows an attacker who is authenticated on the same Microsoft Active Directory domain as a Citrix StoreFront server to read arbitrary files from that server.
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Analysis
by VulDB Data Team • 09/19/2020
The vulnerability identified as CVE-2020-8200 represents a critical authentication flaw in Citrix StoreFront Server versions prior to 1912.0.1000 that fundamentally undermines the security boundaries of the affected systems. This weakness stems from improper authentication mechanisms that fail to adequately validate user credentials and authorization levels, creating a pathway for lateral movement within Active Directory environments. The vulnerability specifically affects scenarios where an attacker has already established authentication within the same Microsoft Active Directory domain as the targeted Citrix StoreFront server, eliminating the need for additional credential compromise or advanced exploitation techniques.
The technical implementation of this flaw resides in the server's authentication handling processes where insufficient validation occurs during the authentication workflow. When users authenticate through the Citrix StoreFront server, the system fails to properly enforce access controls that should restrict file access based on user privileges and roles. This authentication bypass allows attackers to exploit the server's file system access mechanisms without proper authorization, enabling them to read arbitrary files from the targeted system. The vulnerability essentially permits authenticated domain users to access sensitive files that should remain protected, including configuration files, credential stores, and potentially sensitive application data that could contain administrative credentials or encryption keys.
The operational impact of CVE-2020-8200 extends far beyond simple information disclosure, as it provides attackers with access to critical system components that can serve as launching points for further compromise. In a typical enterprise environment, the Citrix StoreFront server often serves as a critical access point for remote workers and internal users, making it a valuable target for attackers seeking to escalate privileges or extract sensitive information. The ability to read arbitrary files can expose configuration settings that reveal network topology, system architecture, and potentially administrative credentials stored in configuration files. This vulnerability aligns with CWE-287 which addresses improper authentication issues, and represents a significant weakness in the principle of least privilege enforcement within the Citrix platform.
Organizations affected by this vulnerability face substantial risk of data breaches, privilege escalation, and potential lateral movement throughout their network infrastructure. The attack vector is particularly concerning because it requires only domain-level authentication, meaning that an attacker who has obtained domain user credentials through phishing, credential theft, or other means can leverage this vulnerability to access sensitive server files. This scenario fits within the ATT&CK framework under the T1078 technique for Valid Accounts and T1566 for Phishing, as the initial compromise can occur through social engineering while the exploitation leverages the authentication bypass. The vulnerability also represents a critical weakness in the defense-in-depth strategy, as it allows attackers to bypass multiple layers of security controls that should normally protect the server's file system.
Mitigation strategies for CVE-2020-8200 must focus on immediate remediation through the installation of the vendor-provided patch for Citrix StoreFront Server version 1912.0.1000 or later, which addresses the authentication flaw through proper access control enforcement. Organizations should implement additional monitoring and logging of file access attempts on Citrix StoreFront servers, particularly for unusual file read patterns that could indicate exploitation attempts. Network segmentation and access control measures should be reviewed to ensure that Citrix StoreFront servers are not directly accessible from untrusted networks, and that appropriate firewall rules are implemented to limit access to only necessary systems. The implementation of principle of least privilege should be enforced where domain users have minimal required access to Citrix StoreFront servers, and additional authentication controls such as multi-factor authentication should be considered for administrative access to these critical systems. Regular security assessments should be conducted to identify and remediate similar authentication bypass vulnerabilities within the organization's infrastructure.