CVE-2017-4964 in BOSH Azure CPI
Summary
by MITRE
Cloud Foundry Foundation BOSH Azure CPI v22 could potentially allow a maliciously crafted stemcell to execute arbitrary code on VMs created by the director, aka a "CPI code injection vulnerability."
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Analysis
by VulDB Data Team • 08/26/2020
The Cloud Foundry Foundation BOSH Azure CPI v22 vulnerability represents a critical code injection flaw that undermines the security posture of cloud infrastructure deployments. This vulnerability specifically affects the Cloud Foundry BOSH deployment toolchain, which is widely used for managing and automating cloud applications. The issue stems from the Azure CPI (Cloud Provider Interface) component that facilitates communication between BOSH and Microsoft Azure cloud services. When a maliciously crafted stemcell is introduced into the system, the vulnerability allows unauthorized code execution on virtual machines created by the BOSH director, effectively compromising the entire deployment infrastructure.
The technical flaw resides in the insufficient validation and sanitization of stemcell content within the CPI component. A stemcell in Cloud Foundry represents a pre-configured virtual machine image that serves as the foundation for deploying applications. When the BOSH director processes a malicious stemcell, the compromised CPI code injection vulnerability enables an attacker to inject and execute arbitrary code within the target virtual machine environment. This occurs because the system fails to properly validate the integrity and authenticity of the stemcell content before deployment, creating an attack vector that bypasses normal security controls and access restrictions.
The operational impact of this vulnerability extends far beyond simple code execution, as it fundamentally compromises the trust model of cloud deployments. Attackers who successfully exploit this vulnerability can gain persistent access to virtual machines, potentially leading to data breaches, service disruption, and lateral movement within cloud networks. The vulnerability affects all systems using BOSH Azure CPI v22, making it particularly dangerous in enterprise environments where multiple applications and services depend on secure cloud infrastructure. The compromised VMs become potential entry points for attackers to escalate privileges, exfiltrate sensitive data, or use the compromised systems as launchpads for attacks against other network segments.
Mitigation strategies for this vulnerability require immediate patching of the BOSH Azure CPI component to version 23 or later, which includes proper input validation and code sanitization measures. Organizations should implement strict stemcell verification processes using cryptographic signatures and integrity checks before deployment. Network segmentation and monitoring should be enhanced to detect unauthorized code execution attempts, while access controls should be reviewed to ensure only authorized personnel can introduce stemcells into the deployment pipeline. The vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and maps to ATT&CK technique T1059, "Command and Scripting Interpreter," highlighting the code execution capabilities that attackers can leverage through this flaw. Additionally, organizations should consider implementing automated security scanning of stemcell content and establishing secure software supply chain practices to prevent malicious code injection at the source.