CVE-2021-33668 in SCIMono
Summary
by MITRE • 06/09/2021
Due to improper input sanitization, specially crafted LDAP queries can be injected by an unauthenticated user. This could partially impact the confidentiality of the application.
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Analysis
by VulDB Data Team • 06/12/2021
The vulnerability identified as CVE-2021-33668 represents a critical security flaw in applications that utilize Lightweight Directory Access Protocol for authentication and authorization purposes. This issue stems from inadequate input validation mechanisms within the LDAP query processing pipeline, allowing malicious actors to inject arbitrary LDAP filter syntax without proper authentication. The vulnerability specifically affects systems where LDAP queries are constructed dynamically based on user input, creating an environment susceptible to injection attacks that can bypass normal access controls and potentially expose sensitive directory information.
The technical root cause of this vulnerability aligns with CWE-94, which describes improper control of generation of code, and more specifically CWE-74, which addresses injection flaws. The flaw manifests when applications fail to properly sanitize or escape user-supplied input before incorporating it into LDAP search filters. This allows attackers to craft malicious queries that can manipulate the LDAP search behavior, potentially retrieving unauthorized data or even executing destructive operations against the directory service. The vulnerability operates at the application layer and requires no authentication to exploit, making it particularly dangerous as it can be leveraged by anyone with access to the affected system's network.
The operational impact of CVE-2021-33668 extends beyond simple data exposure, as it can enable attackers to perform reconnaissance activities against the directory service and potentially escalate privileges within the authenticated environment. Attackers can construct queries that bypass access controls, retrieve sensitive information such as user credentials, group memberships, and other directory attributes that should remain confidential. This vulnerability can be exploited to perform information gathering activities that support more sophisticated attacks, including credential harvesting for lateral movement within the network. The partial impact on confidentiality means that while complete system compromise may not be guaranteed, sufficient information can be extracted to facilitate further attacks.
From a threat modeling perspective, this vulnerability maps to several ATT&CK techniques including T1078 for valid accounts and T1087 for account discovery, as attackers can leverage the injected queries to enumerate users and groups within the directory service. The attack chain typically begins with reconnaissance to identify vulnerable systems, followed by crafting of malicious LDAP queries that exploit the sanitization flaw. Organizations using applications that rely on LDAP for authentication should consider implementing comprehensive input validation, parameterized queries, and proper access controls to prevent unauthorized data access. The vulnerability also highlights the importance of following secure coding practices and implementing proper input sanitization mechanisms, particularly when dealing with directory service protocols that handle sensitive authentication and authorization data.