CVE-2018-10874 in Ansible
Summary
by MITRE
In ansible it was found that inventory variables are loaded from current working directory when running ad-hoc command which are under attacker's control, allowing to run arbitrary code as a result.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-10874 resides within the Ansible automation platform, specifically affecting how inventory variables are processed during ad-hoc command execution. This flaw represents a critical security oversight that allows remote attackers to execute arbitrary code on systems running Ansible. The vulnerability stems from Ansible's improper handling of inventory files located in the current working directory when executing ad-hoc commands, creating a path traversal and code injection vector that can be exploited by malicious actors.
Technical exploitation of this vulnerability occurs when an attacker controls or can influence inventory files present in the working directory where Ansible commands are executed. The flaw manifests because Ansible automatically loads and processes inventory variables from the current working directory without proper sanitization or validation of file contents. When an ad-hoc command is executed, Ansible parses these inventory files and evaluates any variable definitions they contain, potentially executing malicious code embedded within these variables. This behavior directly violates secure coding principles and represents a classic case of insecure deserialization combined with improper input validation. The vulnerability aligns with CWE-74, which addresses "Improper Neutralization of Special Elements in Output Used by a Downstream Component" and CWE-94, covering "Improper Control of Generation of Code ('Code Injection')".
The operational impact of CVE-2018-10874 extends beyond simple code execution, as it can lead to complete system compromise when attackers leverage this vulnerability in conjunction with other attack vectors. In enterprise environments where Ansible is extensively used for configuration management and automation, this vulnerability could enable attackers to escalate privileges, establish persistent access, or deploy additional malware. The attack surface is particularly wide since Ansible is commonly used in CI/CD pipelines, security automation frameworks, and infrastructure-as-code deployments where ad-hoc commands are frequently executed. This vulnerability also maps to ATT&CK technique T1059.001, "Command and Scripting Interpreter: PowerShell", as the arbitrary code execution capability can be used to invoke PowerShell scripts or other system commands. The risk is amplified when considering that many organizations use Ansible with elevated privileges or in environments where the working directory may be accessible to untrusted users or processes.
Mitigation strategies for CVE-2018-10874 should focus on both immediate defensive measures and long-term architectural improvements. Organizations should immediately update to Ansible versions that address this vulnerability, typically those released after the patch date of the vulnerability disclosure. The recommended approach includes implementing strict file access controls on directories where Ansible commands are executed, ensuring that only authorized users can create or modify inventory files in these locations. Additionally, administrators should consider implementing directory-based restrictions or using Ansible's built-in inventory validation features to prevent automatic loading of potentially malicious inventory files. Security monitoring should be enhanced to detect unusual patterns in ad-hoc command execution, particularly when commands are run from unexpected directories or when inventory files with unusual content are processed. The vulnerability also highlights the importance of principle of least privilege in automation environments, where Ansible should be configured to run with minimal necessary permissions and avoid executing commands from directories that may contain untrusted input. Organizations should also consider implementing automated security scanning tools that can detect and prevent the execution of potentially malicious inventory files or variables that could lead to code injection attacks.