CVE-2017-2292 in MCollective
Summary
by MITRE
Versions of MCollective prior to 2.10.4 deserialized YAML from agents without calling safe_load, allowing the potential for arbitrary code execution on the server. The fix for this is to call YAML.safe_load on input. This has been tested in all Puppet-supplied MCollective plugins, but there is a chance that third-party plugins could rely on this insecure behavior.
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Analysis
by VulDB Data Team • 10/21/2019
The vulnerability identified as CVE-2017-2292 represents a critical server-side deserialization flaw in MCollective versions prior to 2.10.4. This issue stems from the improper handling of YAML data structures within the agent communication framework, where the system deserializes YAML input without employing safe loading mechanisms. The flaw exists in the core deserialization process that MCollective uses to process data exchanged between agents and the server, creating a pathway for malicious actors to execute arbitrary code on affected systems. The vulnerability is particularly concerning because it affects the fundamental communication layer of the MCollective infrastructure, which is widely used for configuration management and orchestration tasks in enterprise environments.
The technical root cause of this vulnerability aligns with CWE-502, which specifically addresses deserialization of untrusted data. When MCollective agents process YAML input, the system uses standard YAML loading functions that can execute arbitrary code during the deserialization process. This occurs because the YAML library's default loading mechanism does not restrict the types of objects that can be instantiated during deserialization, allowing attackers to craft malicious YAML payloads that, when processed, execute unintended commands on the target server. The vulnerability is classified as a remote code execution flaw since attackers can exploit this through network-based communication with the MCollective server, requiring no local access or authentication.
The operational impact of CVE-2017-2292 extends beyond simple code execution, as it can lead to complete system compromise and lateral movement within networks where MCollective is deployed. Attackers exploiting this vulnerability can gain unauthorized access to critical infrastructure management systems, potentially escalating privileges, exfiltrating sensitive configuration data, or using the compromised server as a pivot point for further attacks. The flaw affects the core functionality of MCollective's agent-based architecture, where any agent that communicates with the server could serve as an attack vector. This vulnerability particularly impacts organizations using Puppet Enterprise or other Puppet-based infrastructure management solutions, as MCollective is a fundamental component of these platforms. The security implications are compounded by the fact that the fix requires code changes in the core MCollective framework, which may not be immediately implemented across all deployments.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to MCollective version 2.10.4 or later, which properly implements YAML.safe_load to prevent arbitrary code execution. The remediation process should also include thorough review of third-party plugins that may have relied on the insecure deserialization behavior, as these components could introduce additional attack vectors or break functionality after the fix is applied. Security teams should monitor for signs of exploitation attempts and implement network-based detection measures to identify potential malicious YAML payloads. The vulnerability demonstrates the importance of following secure coding practices, particularly when handling untrusted data, and aligns with ATT&CK technique T1059 for command and scripting interpreter, as the exploitation results in arbitrary code execution. Organizations should also consider implementing additional security controls such as network segmentation, access controls, and monitoring of MCollective communication to reduce the risk of successful exploitation and limit potential damage from future similar vulnerabilities.