CVE-2019-3786 in BOSH Backup
Summary
by MITRE
Cloud Foundry BOSH Backup and Restore CLI, all versions prior to 1.5.0, does not check the authenticity of backup scripts in BOSH. A remote authenticated malicious user can modify the metadata file of a Bosh Backup and Restore job to request extra backup files from different jobs upon restore. The exploited hooks in this metadata script were only maintained in the cfcr-etcd-release, so clusters deployed with the BBR job for etcd in this release are vulnerable.
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Analysis
by VulDB Data Team • 09/06/2023
The vulnerability identified as CVE-2019-3786 affects Cloud Foundry BOSH Backup and Restore CLI versions prior to 1.5.0, representing a critical security flaw in the backup and restore functionality of BOSH deployments. This issue stems from insufficient authentication checks during the backup restoration process, specifically within the metadata file handling mechanism of BOSH backup jobs. The vulnerability allows for arbitrary code execution through manipulation of backup script metadata, creating a significant attack surface for malicious actors who can exploit this weakness to compromise the integrity of backup operations.
The technical flaw manifests in the improper validation of backup script metadata files, where the BOSH Backup and Restore CLI fails to authenticate or verify the integrity of backup scripts before execution. This weakness enables authenticated attackers to modify the metadata file associated with BOSH backup and restore jobs, specifically targeting the cfcr-etcd-release which contains exploited hooks in its backup scripts. The vulnerability operates at the intersection of configuration management and privilege escalation, allowing attackers to request additional backup files from different jobs during the restore process, effectively bypassing normal access controls and authorization mechanisms.
The operational impact of this vulnerability extends beyond simple data integrity concerns to encompass complete system compromise potential. Attackers can leverage this flaw to execute unauthorized backup operations, potentially gaining access to sensitive data stored in etcd clusters and other backup components. The vulnerability affects BOSH deployments using the cfcr-etcd-release, which is commonly deployed in Cloud Foundry Container Runtime environments, making it particularly dangerous for organizations relying on these platforms for containerized applications and microservices architectures. This weakness directly impacts the principle of least privilege and can enable attackers to escalate their privileges within the backup infrastructure.
Organizations should implement immediate mitigations including upgrading to BOSH Backup and Restore CLI version 1.5.0 or later, which includes proper authentication checks for backup scripts. Network segmentation and access control measures should be enhanced to restrict unauthorized access to backup operations, while regular security audits should verify the integrity of backup metadata files. The vulnerability aligns with CWE-284 (Improper Access Control) and CWE-434 (Unrestricted Upload of File with Dangerous Type) categories, and maps to ATT&CK techniques including T1078 (Valid Accounts) and T1566 (Phishing) for initial access, followed by T1059 (Command and Scripting Interpreter) for execution. Organizations must also establish automated monitoring for unauthorized metadata modifications and implement proper backup file integrity verification mechanisms to prevent exploitation of this vulnerability in their Cloud Foundry environments.