CVE-2019-11278 in UAA
Summary
by MITRE
CF UAA versions prior to 74.1.0, allow external input to be directly queried against. A remote malicious user with 'client.write' and 'groups.update' can craft a SCIM query, which leaks information that allows an escalation of privileges, ultimately allowing the malicious user to gain control of UAA scopes they should not have.
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Analysis
by VulDB Data Team • 12/28/2023
The vulnerability identified as CVE-2019-11278 affects Cloud Foundry User Account and Authentication (UAA) systems prior to version 74.1.0, representing a critical authorization bypass flaw that stems from improper handling of external input within SCIM query operations. This vulnerability specifically targets the UAA's SCIM (System for Cross-domain Identity Management) implementation, which is responsible for managing user identities and access controls within Cloud Foundry environments. The flaw allows malicious actors to construct specially crafted SCIM queries that can extract sensitive information about user accounts and their associated scopes, effectively undermining the security model that should prevent unauthorized access to privileged resources.
The technical implementation of this vulnerability resides in how the UAA system processes external input when executing SCIM queries against user databases. When a user with sufficient privileges holds the 'client.write' and 'groups.update' permissions, they can manipulate the query parameters to retrieve information about other users within the system. This occurs because the system fails to properly sanitize or validate user-supplied input before incorporating it into database queries, creating an information disclosure vulnerability that can be exploited through what is known as a SQL injection-like attack vector within the SCIM interface. The vulnerability operates under CWE-20, which describes improper input validation, and represents a classic case of insufficient access control enforcement. The attack leverages the legitimate SCIM query functionality to extract data that should remain confidential, allowing for privilege escalation through information gathering rather than direct exploitation.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables a malicious actor to systematically enumerate user accounts and their associated permissions, ultimately allowing them to identify high-privilege users and their scope assignments. This reconnaissance phase can lead to further exploitation attempts, including targeted attacks against specific user accounts or attempts to escalate privileges by leveraging knowledge of other users' access rights. The vulnerability particularly affects Cloud Foundry deployments where the UAA service is exposed to untrusted networks or where users with 'client.write' and 'groups.update' permissions are not properly restricted. According to ATT&CK framework, this vulnerability maps to T1078 (Valid Accounts) and T1566 (Phishing) as attackers can use the leaked information to craft more sophisticated attacks against legitimate accounts, and T1565 (Data Manipulation) as the privilege escalation can lead to unauthorized modification of user accounts. Organizations using affected UAA versions face significant risk of unauthorized access to sensitive user data, potential compromise of privileged accounts, and possible unauthorized modification of user scopes and permissions.
The mitigation strategy for CVE-2019-11278 requires immediate upgrade of UAA components to version 74.1.0 or later, which includes proper input validation and sanitization for SCIM query parameters. Organizations should also implement network segmentation to limit access to the UAA service, restrict the 'client.write' and 'groups.update' permissions to only essential administrative users, and establish monitoring for unusual SCIM query patterns that might indicate exploitation attempts. Additional defensive measures include implementing strict access controls for SCIM endpoints, regular security auditing of user permissions, and ensuring that the principle of least privilege is enforced across all UAA-managed resources. The fix addresses the root cause by implementing proper parameter binding and input validation mechanisms that prevent malicious input from being directly incorporated into database queries, thereby eliminating the attack vector that enabled the information disclosure and privilege escalation.