CVE-2016-4972 in Murano
Summary
by MITRE
OpenStack Murano before 1.0.3 (liberty) and 2.x before 2.0.1 (mitaka), Murano-dashboard before 1.0.3 (liberty) and 2.x before 2.0.1 (mitaka), and python-muranoclient before 0.7.3 (liberty) and 0.8.x before 0.8.5 (mitaka) improperly use loaders inherited from yaml.Loader when parsing MuranoPL and UI files, which allows remote attackers to create arbitrary Python objects and execute arbitrary code via crafted extended YAML tags in UI definitions in packages.
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Analysis
by VulDB Data Team • 04/26/2019
The vulnerability identified as CVE-2016-4972 represents a critical security flaw in OpenStack Murano platforms and related components. This issue affects multiple versions of Murano including the liberty release before 1.0.3 and the mitaka release before 2.0.1, along with their corresponding dashboard and client libraries. The vulnerability stems from improper handling of YAML parsing operations within the Murano platform's package definition system, creating a significant attack surface that could be exploited by remote adversaries. The flaw specifically manifests in how the system processes extended YAML tags during the parsing of MuranoPL files and user interface definitions within packages, allowing attackers to manipulate the parsing behavior to execute malicious code.
The technical root cause of this vulnerability lies in the insecure use of yaml.Loader inheritance patterns when processing package definitions. When Murano parses UI files and MuranoPL content, it inadvertently accepts and processes extended YAML tags that are designed to create arbitrary Python objects during deserialization. This behavior directly violates secure coding principles and creates a path for arbitrary code execution attacks. The vulnerability operates under CWE-502 which specifically addresses "Deserialization of Untrusted Data" and aligns with ATT&CK technique T1059.006 for "Command and Scripting Interpreter: Python" as attackers can leverage this flaw to execute Python commands within the context of the affected system. The flaw is particularly dangerous because it allows attackers to bypass normal security controls and execute code with the privileges of the Murano service itself.
The operational impact of CVE-2016-4972 extends beyond simple code execution to encompass complete system compromise potential. Attackers who successfully exploit this vulnerability can gain unauthorized access to OpenStack environments, potentially leading to data breaches, service disruption, or further lateral movement within cloud infrastructures. The vulnerability affects not just the core Murano platform but also its dashboard and client components, meaning that an attacker could potentially compromise any system component that processes package definitions. This creates cascading security implications as the attack surface expands across multiple layers of the OpenStack ecosystem. Organizations using affected versions of Murano are particularly vulnerable because the flaw can be exploited through package uploads, which are common operations in cloud deployment scenarios, making the attack vector both accessible and potentially automated.
Mitigation strategies for CVE-2016-4972 require immediate patching of all affected versions to the recommended secure releases. Organizations should upgrade to Murano 1.0.3 or later for liberty releases and 2.0.1 or later for mitaka releases, along with corresponding updates to murano-dashboard and python-muranoclient components. Beyond patching, system administrators should implement additional protective measures including network segmentation to limit access to Murano services, strict package validation procedures, and monitoring for unusual package upload activities. The vulnerability demonstrates the critical importance of secure deserialization practices and proper input validation in cloud platforms, aligning with security frameworks that emphasize the need for least privilege access and defense in depth strategies. Security teams should also consider implementing automated vulnerability scanning tools that can detect similar insecure YAML parsing patterns in other applications within their environment, as this type of flaw can appear in various software systems that rely on YAML processing.