CVE-2021-35249 in Serv-U
Summary
by MITRE • 05/18/2022
This broken access control vulnerability pertains specifically to a domain admin who can access configuration & user data of other domains which they should not have access to. Please note the admin is unable to modify the data (read only operation). This UAC issue leads to a data leak to unauthorized users for a domain, with no log of them accessing the data unless they attempt to modify it. This read-only activity is logged to the original domain and does not specify which domain was accessed.
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Analysis
by VulDB Data Team • 09/27/2024
This vulnerability represents a critical broken access control flaw that undermines fundamental security boundaries within multi-domain environments. The issue manifests when a domain administrator gains unauthorized read access to configuration and user data from other domains without proper authorization, creating a significant data exposure risk. The vulnerability specifically affects privileged users who should be restricted to their designated domain scope but instead can traverse domain boundaries through a misconfigured access control mechanism. This represents a direct violation of the principle of least privilege and domain isolation principles that are essential for maintaining security boundaries in enterprise environments.
The technical implementation of this vulnerability stems from improper access control validation mechanisms that fail to enforce domain-specific boundaries during read operations. While the attacker cannot modify data, the read-only access still constitutes a severe information disclosure vulnerability that allows for comprehensive reconnaissance and data collection. The lack of proper logging for read operations creates a significant blind spot in security monitoring, as unauthorized access attempts leave no audit trail for detection. This absence of logging specifically affects the ability to track which domain was accessed, making it impossible for security teams to identify the scope of the compromise or correlate access patterns across different domains.
The operational impact of this vulnerability extends beyond simple data exposure, as it enables attackers to gather sensitive information about other domains including user configurations, system settings, and potentially identifying details that could be leveraged for further attacks. The read-only nature of the access does not diminish the severity since it allows for comprehensive reconnaissance without leaving obvious traces in audit logs. This vulnerability aligns with CWE-284 which addresses improper access control and specifically relates to inadequate access control mechanisms that allow unauthorized access to resources. The lack of logging for read operations also violates security monitoring best practices and creates gaps in the defense-in-depth strategy.
Organizations affected by this vulnerability face significant risk of data leakage and potential lateral movement attacks that could escalate to full domain compromise. The absence of proper logging means that security teams cannot detect unauthorized access patterns or identify compromised accounts, creating a false sense of security. This vulnerability can be exploited by malicious insiders or external attackers who gain domain admin credentials, potentially leading to extensive data exposure across multiple domains. The issue directly impacts the integrity of domain isolation policies and creates opportunities for attackers to build comprehensive profiles of target environments. Mitigation strategies should include implementing proper access control validation at domain boundaries, enabling comprehensive logging for all read operations, and establishing monitoring rules that can detect anomalous cross-domain access patterns. The vulnerability also highlights the importance of regular security testing and access control reviews to identify and remediate similar issues before they can be exploited.