CVE-2017-2809 in Ansible Vault
Summary
by MITRE
An exploitable vulnerability exists in the yaml loading functionality of Ansible Vault before 1.0.5. A specially crafted vault can execute arbitrary python commands resulting in command execution. An attacker can insert python into the vault to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/29/2022
The vulnerability identified as CVE-2017-2809 represents a critical security flaw in Ansible Vault's yaml loading mechanism prior to version 1.0.5. This issue falls under the category of code injection vulnerabilities and specifically demonstrates how improper handling of serialized data can lead to arbitrary code execution. The vulnerability stems from Ansible Vault's reliance on Python's yaml loading functionality without proper sanitization of input data, creating an attack surface where malicious actors can craft specially formatted vault files that contain executable Python code.
The technical exploitation of this vulnerability occurs through the manipulation of yaml data structures within Ansible Vault files. When Ansible processes these vault files, it deserializes the yaml content using Python's default yaml loader which, by design, can execute arbitrary Python objects during the parsing process. Attackers can embed malicious Python code within the yaml structure that gets executed when the vault is loaded, effectively bypassing normal security boundaries and gaining unauthorized command execution capabilities on systems where Ansible Vault is deployed. This vulnerability directly maps to CWE-94, which describes the weakness of "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK technique T1059.006 for "Command and Scripting Interpreter: Python".
The operational impact of this vulnerability extends beyond simple command execution as it fundamentally undermines the security model of Ansible Vault, which is designed to protect sensitive configuration data. An attacker who can influence or compromise the contents of an Ansible Vault file can escalate privileges to the level of the user executing the ansible commands, potentially leading to full system compromise. The vulnerability is particularly dangerous in environments where Ansible is used for configuration management across multiple systems, as a single compromised vault file can affect the entire infrastructure. Organizations relying on Ansible Vault for secrets management face significant risk of data breaches, privilege escalation, and unauthorized access to critical systems when this vulnerability remains unpatched.
Mitigation strategies for CVE-2017-2809 primarily focus on immediate patching of Ansible Vault installations to version 1.0.5 or later, which addresses the underlying yaml loading issue through proper input sanitization and validation. Additionally, organizations should implement strict access controls and audit procedures for vault files, ensuring that only authorized personnel can modify sensitive configuration data. The implementation of principle of least privilege should be enforced when running Ansible commands, limiting the potential damage from successful exploitation. Security monitoring should include detection of unusual vault file modifications and execution patterns that might indicate exploitation attempts. Organizations should also consider implementing additional layers of security such as code signing for vault files and regular security assessments of their Ansible configurations to prevent similar vulnerabilities from emerging in other components of their automation infrastructure.