CVE-2018-1104 in Ansible Tower
Summary
by MITRE
Ansible Tower through version 3.2.3 has a vulnerability that allows users only with access to define variables for a job template to execute arbitrary code on the Tower server.
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Analysis
by VulDB Data Team • 08/22/2022
The vulnerability identified as CVE-2018-1104 represents a critical privilege escalation flaw within Ansible Tower versions up to 3.2.3 that fundamentally undermines the security model of the platform. This issue arises from insufficient input validation and sanitization mechanisms within the job template variable handling system, creating a pathway for unauthorized code execution on the Ansible Tower server itself. The vulnerability specifically targets users who possess only the limited permission to define variables for job templates, which typically should not grant them the ability to execute arbitrary commands on the underlying system. This flaw demonstrates a classic case of improper access control where the system fails to properly validate that variable inputs do not contain malicious payloads designed to exploit the underlying execution environment.
The technical exploitation of this vulnerability occurs through the manipulation of job template variables that are processed by the Ansible Tower server without adequate sanitization. When a user with variable definition privileges submits crafted variable content, the system processes these inputs directly within the execution context of the Tower server, potentially allowing for command injection attacks. The vulnerability leverages the trust placed in user-supplied variables within the job execution pipeline, where variable interpolation and template processing can be manipulated to execute arbitrary shell commands or code on the server hosting Ansible Tower. This represents a severe breakout from the intended security boundaries of the platform, as the normal operational constraints of job template variable handling are bypassed to achieve system-level code execution.
The operational impact of CVE-2018-1104 is profound and potentially catastrophic for organizations relying on Ansible Tower for infrastructure automation and orchestration. An attacker exploiting this vulnerability could gain complete control over the Ansible Tower server, potentially leading to unauthorized access to sensitive automation workflows, credential theft, and the ability to execute commands across all managed systems within the automation environment. The attack vector is particularly dangerous because it requires minimal privileges to exploit, making it accessible to users who should normally be restricted to variable definition tasks. This vulnerability effectively neutralizes the principle of least privilege within the Ansible Tower security model, as the system fails to properly isolate user inputs from the execution environment. Organizations using Ansible Tower may find their entire automation infrastructure compromised, with potential for lateral movement to other systems within the network that are managed through Ansible.
Organizations should immediately implement mitigations including updating to Ansible Tower version 3.2.4 or later, which contains the necessary patches to address this vulnerability. Additionally, administrators should review and restrict user permissions, ensuring that users with variable definition privileges are not granted unnecessary access to job execution capabilities. The implementation of input validation and sanitization measures for all user-supplied variables within job templates should be enforced, along with monitoring for anomalous variable usage patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-74 and CWE-94 categories, representing code injection and improper neutralization of special elements in the context of command execution. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, demonstrating how a seemingly limited privilege escalation can result in full system compromise. The vulnerability also highlights the importance of the principle of least privilege and proper input validation in maintaining secure automation platforms.