CVE-2019-3785 in Cloud Foundry Cloud Controller
Summary
by MITRE
Cloud Foundry Cloud Controller, versions prior to 1.78.0, contain an endpoint with improper authorization. A remote authenticated malicious user with read permissions can request package information and receive a signed bit-service url that grants the user write permissions to the bit-service.
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Analysis
by VulDB Data Team • 08/01/2023
The Cloud Foundry Cloud Controller vulnerability identified as CVE-2019-3785 represents a critical authorization flaw that undermines the security model of the platform. This vulnerability exists in versions prior to 1.78.0 and demonstrates a classic case of insufficient access control where a user with minimal privileges can escalate their capabilities through a carefully crafted API request. The flaw specifically targets the package information endpoint, which should normally be restricted to authorized users with appropriate permissions. However, the implementation fails to properly validate user credentials when generating signed URLs for bit-service operations, creating an unauthorized access vector that allows malicious actors to obtain write permissions.
The technical mechanism behind this vulnerability involves the improper handling of authentication tokens and permission scopes within the Cloud Controller's API layer. When a user with read-only permissions requests package information, the system generates a signed URL that includes a service endpoint for bit-service operations. The flaw lies in the fact that this signed URL contains sufficient credentials or tokens to grant write access to the bit-service, even though the initiating user lacks such permissions. This represents a violation of the principle of least privilege and demonstrates poor separation of concerns in the authorization system. The vulnerability falls under CWE-285, which specifically addresses improper authorization issues in software systems, and aligns with ATT&CK technique T1078 for valid accounts and T1566 for phishing with social engineering.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it creates a persistent security risk for organizations using affected Cloud Foundry deployments. A malicious user could potentially modify package content, inject malicious code, or disrupt service delivery by leveraging the elevated write permissions granted through the forged signed URL. This vulnerability particularly affects cloud-native environments where package management and deployment automation are critical components of the application lifecycle. The implications are severe because Cloud Foundry deployments often host multiple applications and services, making a single compromised package endpoint a potential gateway for broader system compromise. Organizations may experience data integrity issues, service disruption, and potential compliance violations if packages are modified without proper authorization.
Mitigation strategies for CVE-2019-3785 require immediate action to upgrade affected Cloud Controller instances to version 1.78.0 or later, which contains the necessary authorization fixes. System administrators should also implement additional monitoring of package-related API endpoints to detect unusual access patterns or unauthorized URL generation requests. The remediation process should include reviewing and tightening access controls for all endpoints that generate signed URLs, ensuring that token generation properly validates user permissions before granting elevated capabilities. Organizations should also consider implementing network segmentation and API rate limiting to reduce the impact of potential exploitation attempts. Security teams should conduct thorough audits of their Cloud Foundry deployments to identify any other endpoints that might exhibit similar authorization flaws, as this vulnerability demonstrates the importance of comprehensive access control validation throughout the application architecture.