CVE-2018-6508 in Puppet Enterprise
Summary
by MITRE
Puppet Enterprise 2017.3.x prior to 2017.3.3 are vulnerable to a remote execution bug when a specially crafted string was passed into the facter_task or puppet_conf tasks. This vulnerability only affects tasks in the affected modules, if you are not using puppet tasks you are not affected by this vulnerability.
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Analysis
by VulDB Data Team • 01/03/2020
This vulnerability affects Puppet Enterprise versions 2017.3.x prior to 2017.3.3 and represents a critical remote code execution flaw within the task execution framework. The vulnerability manifests when specially crafted strings are passed into either the facter_task or puppet_conf tasks, which are part of Puppet's task management system designed to execute commands on managed nodes. The flaw stems from insufficient input validation and sanitization within the task processing pipeline, allowing attackers to inject malicious payloads that get executed with the privileges of the Puppet Enterprise service account. This represents a direct violation of the principle of least privilege and creates a severe attack surface for unauthorized code execution across managed infrastructure.
The technical implementation of this vulnerability involves improper handling of user-supplied input within the task execution mechanism, creating a classic command injection scenario. When the affected tasks process input parameters, they fail to properly escape or validate special characters that could be interpreted as shell commands. This allows an attacker to craft malicious input strings that bypass normal security controls and execute arbitrary commands on target systems. The vulnerability specifically impacts the facter_task which gathers system information and puppet_conf task which manages puppet configuration, both of which are legitimate administrative functions that can be invoked remotely. This aligns with CWE-77 and CWE-78 categories related to command injection vulnerabilities, where improper input validation leads to arbitrary code execution.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary code on managed nodes without authentication, potentially leading to complete system compromise. Attackers can leverage this vulnerability to escalate privileges, install backdoors, exfiltrate sensitive data, or establish persistent access to the Puppet Enterprise infrastructure. The vulnerability affects the entire Puppet Enterprise ecosystem since it operates at the task execution layer, meaning any managed node that has tasks enabled and is accessible to the attacker could be compromised. This aligns with ATT&CK technique T1059.001 for command and scripting interpreter, where adversaries use legitimate system tools to execute malicious commands. Organizations using Puppet tasks for automation, configuration management, or system administration are at significant risk as the attack vector requires no prior authentication credentials.
Organizations should immediately upgrade to Puppet Enterprise 2017.3.3 or later versions to remediate this vulnerability. The patch addresses the input validation issues by implementing proper sanitization of task parameters and ensuring that special characters are properly escaped before processing. Administrators should also review task configurations to minimize the attack surface, disable unnecessary tasks, and implement network segmentation to limit access to Puppet Enterprise servers. Additional mitigations include monitoring for suspicious task execution patterns, implementing strict access controls for task invocation, and regularly auditing task usage within the Puppet infrastructure. Security teams should also consider implementing network-based intrusion detection systems to detect anomalous task execution patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of validating all user inputs in administrative interfaces and highlights the need for comprehensive security testing of automation frameworks that handle privileged operations.