CVE-2016-6656 in Greenplum
Summary
by MITRE
An issue was discovered in Pivotal Greenplum before 4.3.10.0. Creation of external tables using GPHDFS protocol has a vulnerability whereby arbitrary commands can be injected into the system. In order to exploit this vulnerability the user must have superuser 'gpadmin' access to the system or have been granted GPHDFS protocol permissions in order to create a GPHDFS external table.
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Analysis
by VulDB Data Team • 07/09/2019
The vulnerability identified as CVE-2016-6656 represents a critical command injection flaw within Pivotal Greenplum database systems prior to version 4.3.10.0. This security weakness specifically affects the GPHDFS protocol implementation used for creating external tables, creating a significant attack surface that could allow malicious actors to execute arbitrary code on the target system. The vulnerability stems from insufficient input validation and sanitization mechanisms within the external table creation process, particularly when utilizing the GPHDFS protocol which is designed to interface with Hadoop Distributed File System environments. The flaw exists at the protocol level where user-supplied data is not properly escaped or validated before being processed by the underlying system commands.
The technical exploitation of this vulnerability requires either superuser access with the 'gpadmin' account or specific permissions granted to create GPHDFS external tables, making it a privilege-dependent vulnerability that can be leveraged by authenticated attackers. When a user creates an external table using the GPHDFS protocol, the system constructs system commands based on user-provided parameters without adequate sanitization. This creates an environment where malicious input can be injected into the command execution pipeline, allowing attackers to execute arbitrary commands with the privileges of the database process. The vulnerability aligns with CWE-77 and CWE-94 categories, representing command injection flaws that can lead to arbitrary code execution and privilege escalation.
From an operational impact perspective, this vulnerability poses a severe risk to organizations relying on Pivotal Greenplum for data warehousing and analytics operations. Successful exploitation could result in complete system compromise, data exfiltration, or the installation of persistent backdoors. The attack vector is particularly concerning because it requires minimal privileges to exploit, making it accessible to users with limited database access who have been granted specific protocol permissions. This vulnerability can be exploited to gain access to sensitive data stored within the Greenplum environment, potentially leading to compliance violations and significant financial losses.
Organizations should immediately implement mitigations including upgrading to Pivotal Greenplum version 4.3.10.0 or later where this vulnerability has been addressed through proper input validation and sanitization of user-provided parameters. Additionally, administrators should review and restrict permissions for GPHDFS protocol usage, limiting access to only trusted users and applications. Network segmentation and monitoring should be implemented to detect suspicious external table creation activities. The mitigation strategy should also include regular security assessments and privilege reviews to ensure that only necessary users have access to create external tables with potentially dangerous protocols. This vulnerability demonstrates the importance of proper input validation in database systems and aligns with ATT&CK technique T1059 for command and scripting interpreter, highlighting the need for comprehensive security controls in database environments.