CVE-2017-8036 in Cloud Foundry
Summary
by MITRE
An issue was discovered in the Cloud Controller API in Cloud Foundry Foundation CAPI-release version 1.33.0 (only). The original fix for CVE-2017-8033 included in CAPI-release 1.33.0 introduces a regression that allows a space developer to execute arbitrary code on the Cloud Controller VM by pushing a specially crafted application.
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Analysis
by VulDB Data Team • 01/06/2021
The vulnerability CVE-2017-8036 represents a critical regression in the Cloud Foundry Cloud Controller API that emerged in CAPI-release version 1.33.0. This issue specifically affects the Cloud Foundry Foundation's CAPI component and demonstrates how security fixes can sometimes introduce new vulnerabilities. The flaw stems from an improper implementation of access controls within the application pushing mechanism, creating an exploitable condition that allows unauthorized code execution on the Cloud Controller VM itself. The vulnerability is particularly concerning because it specifically targets space developers, who typically have limited permissions within a Cloud Foundry environment, yet can leverage this flaw to escalate their privileges to system-level access. This regression directly undermines the principle of least privilege that is fundamental to cloud security architectures and represents a significant failure in the security testing process of the patch for the previously identified CVE-2017-8033.
The technical flaw manifests through a specific weakness in the application manifest parsing and validation process within the Cloud Controller API. When a space developer attempts to push an application with a specially crafted manifest file, the system fails to properly validate the application metadata, allowing malicious payloads to bypass security checks. This vulnerability operates at the application deployment layer where the Cloud Controller API processes user requests to push applications. The flaw leverages the trust relationship between the Cloud Controller and the application deployment process, enabling an attacker to inject executable code that gets executed within the privileged context of the Cloud Controller VM. The vulnerability is classified as a command injection or code execution flaw that aligns with CWE-77 and CWE-94 categories, representing a direct violation of input validation and privilege separation principles. The attack vector specifically targets the application manifest file processing, where user-supplied data is not adequately sanitized before being processed by the system.
The operational impact of CVE-2017-8036 extends far beyond the immediate compromise of individual applications, as it provides attackers with a foothold to potentially compromise the entire Cloud Controller infrastructure. Space developers who should normally only have the ability to deploy and manage applications within their designated spaces can leverage this vulnerability to execute arbitrary code on the Cloud Controller VM, potentially gaining access to sensitive configuration data, user credentials, and other system resources. The implications are particularly severe in multi-tenant environments where multiple organizations share the same Cloud Foundry instance, as a single compromised space developer account could potentially lead to lateral movement and privilege escalation across multiple applications and potentially other system components. This vulnerability directly violates the security model of Cloud Foundry by allowing privilege escalation from a limited developer role to system-level access, creating potential data breaches, service disruption, and unauthorized access to critical infrastructure components.
Mitigation strategies for CVE-2017-8036 require immediate action to address the root cause of the vulnerability through proper input validation and access control enforcement. Organizations should upgrade to CAPI-release versions that properly address this regression, ensuring that the fix for CVE-2017-8033 does not introduce new vulnerabilities. The recommended approach includes implementing strict manifest validation that sanitizes all user-supplied input before processing, enforcing proper privilege separation between application deployment and system-level operations, and conducting comprehensive security testing of all patches before deployment. Additionally, organizations should implement monitoring and logging of application deployment activities to detect anomalous behavior that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and execution of malicious code within system processes, specifically targeting the cloud infrastructure layer. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities, ensuring that even if exploitation occurs, lateral movement within the infrastructure is restricted. The fix should include comprehensive testing to prevent similar regressions in future security patches, emphasizing the importance of thorough regression testing in security update processes.