CVE-2017-7481 in Ansible
Summary
by MITRE
Ansible before versions 2.3.1.0 and 2.4.0.0 fails to properly mark lookup-plugin results as unsafe. If an attacker could control the results of lookup() calls, they could inject Unicode strings to be parsed by the jinja2 templating system, resulting in code execution. By default, the jinja2 templating language is now marked as 'unsafe' and is not evaluated.
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Analysis
by VulDB Data Team • 04/18/2023
The vulnerability identified as CVE-2017-7481 represents a critical security flaw in Ansible automation software that affects versions prior to 2.3.1.0 and 2.4.0.0. This issue stems from improper handling of lookup plugin results within Ansible's templating system, creating a potential code execution vector that could be exploited by malicious actors. The vulnerability specifically targets the Jinja2 templating engine integration within Ansible, where lookup plugin outputs are not correctly marked as unsafe, allowing for unauthorized code injection. The flaw demonstrates a fundamental breakdown in input validation and sanitization processes that are essential for maintaining the security boundaries of automation frameworks.
The technical implementation of this vulnerability occurs through the manipulation of lookup plugin results that are subsequently processed by the Jinja2 templating system. When Ansible executes playbooks containing lookup operations, the system should properly sanitize and mark the output from these plugins as unsafe to prevent template evaluation. However, in vulnerable versions, this safety mechanism fails, allowing attackers who can influence lookup plugin inputs to inject malicious Unicode strings that bypass the templating safety checks. The vulnerability specifically exploits the trust relationship between lookup plugins and the templating engine, where untrusted data from external sources can be directly interpreted as executable code within the Jinja2 context.
The operational impact of CVE-2017-7481 extends beyond simple code execution to encompass broader system compromise scenarios. An attacker with the ability to control lookup plugin inputs could potentially execute arbitrary commands on systems where Ansible is deployed, particularly in environments where Ansible is used for configuration management, deployment automation, or security orchestration. This vulnerability affects the integrity of Ansible's security model, as it undermines the principle of least privilege and trust boundaries that should exist between different components of the automation framework. The risk is particularly elevated in multi-tenant environments or when Ansible is used to manage sensitive infrastructure components.
The mitigation strategies for CVE-2017-7481 primarily focus on upgrading to patched versions of Ansible where lookup plugin results are properly marked as unsafe by default. This upgrade addresses the core issue by implementing proper input sanitization and template safety mechanisms that prevent the execution of untrusted content. Organizations should also implement strict access controls and input validation for any custom lookup plugins or external data sources that feed into Ansible operations. The fix aligns with security best practices outlined in CWE-74 and CWE-134, which address injection flaws and improper neutralization of special elements used in template languages. Additionally, this vulnerability demonstrates the importance of implementing defense-in-depth strategies as recommended by ATT&CK framework tactics related to privilege escalation and command execution, ensuring that even if one layer of security is compromised, additional safeguards remain effective.