CVE-2018-6516 in PE Client Tools
Summary
by MITRE
On Windows only, with a specifically crafted configuration file an attacker could get Puppet PE client tools (aka pe-client-tools) 16.4.x prior to 16.4.6, 17.3.x prior to 17.3.6, and 18.1.x prior to 18.1.2 to load arbitrary code with privilege escalation.
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Analysis
by VulDB Data Team • 02/19/2020
The vulnerability identified as CVE-2018-6516 represents a critical privilege escalation flaw affecting Puppet Enterprise client tools on Windows systems. This security issue stems from improper handling of specially crafted configuration files that can trigger arbitrary code execution with elevated privileges. The affected versions include pe-client-tools 16.4.x before 16.4.6, 17.3.x before 17.3.6, and 18.1.x before 18.1.2, making it a widespread concern across multiple major release lines of the Puppet Enterprise platform. The vulnerability specifically targets the Windows implementation of Puppet PE client tools, highlighting the platform-specific nature of the security flaw.
The technical root cause of this vulnerability lies in the insecure processing of configuration files within the Puppet PE client tools framework. When an attacker crafts a malicious configuration file and successfully influences the client tools to load it, the system executes arbitrary code with the privileges of the currently authenticated user. This behavior constitutes a privilege escalation vulnerability that can be exploited to gain elevated system access. The flaw demonstrates poor input validation and secure configuration file handling practices, allowing attackers to manipulate the normal execution flow of the client tools through crafted inputs. This type of vulnerability falls under CWE-20, which describes improper input validation, and more specifically aligns with CWE-78, representing OS command injection, when arbitrary code execution occurs through configuration file manipulation.
The operational impact of CVE-2018-6516 extends beyond simple privilege escalation, as it provides attackers with a potential foothold for further system compromise within enterprise environments. Organizations relying on Puppet Enterprise for configuration management face significant risk when exposed to this vulnerability, as it could enable attackers to execute malicious code with elevated privileges on systems managed by Puppet. The attack vector requires the attacker to influence the loading of a specific configuration file, which might be achieved through various means including social engineering, compromised network infrastructure, or by directly manipulating configuration files on target systems. This vulnerability directly aligns with ATT&CK technique T1068, which covers local privilege escalation through the exploitation of software vulnerabilities, and T1566, covering spearphishing with a malicious file as a potential initial access method.
Organizations should prioritize immediate remediation by upgrading to the patched versions of Puppet PE client tools, specifically versions 16.4.6, 17.3.6, and 18.1.2 respectively. The mitigation strategy should include comprehensive vulnerability scanning to identify affected systems within the enterprise environment, followed by systematic patch deployment across all Windows systems running the vulnerable client tools. Security teams should implement additional monitoring for unusual configuration file modifications and unauthorized access attempts to Puppet-managed systems. Network segmentation and access controls should be reinforced to limit potential lateral movement if an attacker successfully exploits this vulnerability. The remediation process must be carefully coordinated to ensure that configuration file integrity is maintained during the patching process, as the vulnerability specifically targets the loading mechanism of configuration files. Organizations should also consider implementing automated patch management solutions to prevent similar vulnerabilities from remaining unaddressed in future deployments.