CVE-2020-1738 in Ansible Engine
Summary
by MITRE
A flaw was found in Ansible Engine when the module package or service is used and the parameter 'use' is not specified. If a previous task is executed with a malicious user, the module sent can be selected by the attacker using the ansible facts file. All versions in 2.7.x, 2.8.x and 2.9.x branches are believed to be vulnerable.
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Analysis
by VulDB Data Team • 05/10/2025
The vulnerability identified as CVE-2020-1738 represents a critical security flaw within the Ansible Engine ecosystem that fundamentally undermines the integrity of automated deployment and configuration management processes. This vulnerability specifically affects Ansible versions across the 2.7.x, 2.8.x, and 2.9.x release branches, creating a persistent risk for organizations relying on Ansible for infrastructure automation. The flaw manifests when Ansible modules package or service are invoked without explicitly specifying the 'use' parameter, creating an exploitable condition that allows malicious actors to manipulate the execution flow through crafted ansible facts files.
The technical implementation of this vulnerability stems from insufficient input validation and parameter handling within the Ansible module execution engine. When the 'use' parameter remains unspecified, the system defaults to an insecure behavior that permits external influence over module selection processes. This occurs through manipulation of the ansible facts file, which serves as a critical data exchange mechanism between the target system and the Ansible control node. The attacker can craft malicious facts that, when processed by the vulnerable Ansible engine, result in the execution of unintended modules or commands. This represents a classic case of insecure parameter handling and privilege escalation through configuration manipulation, with direct implications for the principle of least privilege in automated systems.
The operational impact of CVE-2020-1738 extends far beyond simple privilege escalation, potentially enabling complete system compromise and unauthorized access to critical infrastructure components. Organizations utilizing Ansible for deployment automation face significant risk when this vulnerability exists in their environments, as it allows attackers to execute arbitrary code on target systems through carefully crafted ansible facts. The vulnerability can be exploited to install backdoors, modify system configurations, exfiltrate sensitive data, or establish persistent access points within the network infrastructure. The attack vector is particularly concerning because it can be initiated through seemingly legitimate automation workflows, making detection and prevention challenging for security teams.
From a cybersecurity framework perspective, this vulnerability maps directly to CWE-20, which describes "Improper Input Validation," and CWE-78, "Improper Neutralization of Special Elements used in OS Command Injection." The attack pattern aligns with ATT&CK techniques including T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation. The vulnerability demonstrates the critical importance of proper parameter validation in automation frameworks and highlights the need for robust input sanitization processes. Organizations should immediately implement mitigation strategies including mandatory parameter validation, comprehensive monitoring of ansible facts file modifications, and strict access controls on automation infrastructure to prevent unauthorized manipulation of configuration data.
Mitigation efforts should prioritize immediate patching of affected Ansible versions to the latest stable releases, which contain the necessary fixes for this vulnerability. Additionally, organizations must implement comprehensive monitoring solutions that track changes to ansible facts files and module execution patterns, enabling detection of anomalous behavior indicative of exploitation attempts. Security teams should conduct thorough assessments of their Ansible automation workflows to ensure that all module invocations properly specify required parameters and implement additional validation checks. Network segmentation and privileged access controls should be enforced to limit the potential impact of successful exploitation attempts, while regular security audits of automation infrastructure help identify and remediate similar vulnerabilities across the broader infrastructure ecosystem.