CVE-2017-12148 in Ansible
Summary
by MITRE
A flaw was found in Ansible Tower's interface before 3.1.5 and 3.2.0 with SCM repositories. If a Tower project (SCM repository) definition does not have the 'delete before update' flag set, an attacker with commit access to the upstream playbook source repository could create a Trojan playbook that, when executed by Tower, modifies the checked out SCM repository to add git hooks. These git hooks could, in turn, cause arbitrary command and code execution as the user Tower runs as.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2017-12148 represents a critical security flaw in Ansible Tower's handling of source control management repositories. This issue affects versions prior to 3.1.5 and 3.2.0, specifically targeting the project definition mechanisms that manage SCM repository synchronization. The vulnerability stems from insufficient security controls during the repository update process, creating a pathway for privilege escalation and arbitrary code execution. The flaw is particularly concerning because it leverages legitimate system functionality to create an attack vector that bypasses normal security boundaries.
The technical implementation of this vulnerability exploits the absence of the 'delete before update' flag in project definitions, which is a critical configuration parameter for secure repository management. When this flag is not set, Ansible Tower performs incremental updates to SCM repositories rather than complete replacements of the working directory. This approach creates a window of opportunity where an attacker with commit access to the upstream repository can manipulate the checkout process by introducing malicious git hooks. The git hooks are strategically placed within the repository structure to execute commands when specific git operations occur, effectively establishing a persistent backdoor within the system.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise. Attackers can leverage this flaw to execute arbitrary commands with the privileges of the Ansible Tower user, which typically runs with elevated permissions to manage system resources and execute playbooks. This privilege escalation capability enables attackers to access sensitive configuration data, manipulate automation workflows, and potentially pivot to other systems within the network infrastructure. The vulnerability's stealth nature makes detection particularly challenging since the malicious activity occurs within legitimate system processes and appears as normal repository operations.
This vulnerability maps directly to CWE-434, which describes insecure file upload or handling of files from untrusted sources, and aligns with ATT&CK technique T1059 for command and scripting interpreter execution. The attack vector follows the pattern of supply chain compromise where attackers manipulate trusted source repositories to introduce malicious code that executes within the target environment. Organizations using Ansible Tower are particularly vulnerable because the flaw operates at the integration layer between source control systems and automation platforms, creating a significant risk for enterprises that rely on automated infrastructure management. The remediation requires immediate implementation of the 'delete before update' flag for all SCM repository definitions, along with comprehensive security auditing of existing project configurations to identify potential exploitation attempts.
Mitigation strategies should include mandatory configuration reviews to ensure all SCM project definitions have the delete before update flag enabled, along with regular security assessments of source repositories. Network segmentation and access controls should be implemented to limit commit privileges to SCM repositories, reducing the attack surface for potential exploitation. Additionally, organizations should establish monitoring procedures to detect unauthorized git hook modifications and implement automated scanning of repository contents for suspicious patterns that might indicate compromise. The vulnerability underscores the critical importance of secure configuration management and proper access controls in automation platforms, as these systems often serve as central points of control for enterprise infrastructure.