CVE-2014-3627 in Hadoop
Summary
by MITRE
The YARN NodeManager daemon in Apache Hadoop 0.23.0 through 0.23.11 and 2.x before 2.5.2, when using Kerberos authentication, allows remote cluster users to change the permissions of certain files to world-readable via a symlink attack in a public tar archive, which is not properly handled during localization, related to distributed cache.
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Analysis
by VulDB Data Team • 04/08/2018
The vulnerability identified as CVE-2014-3627 represents a critical security flaw in Apache Hadoop's YARN NodeManager daemon that affects versions ranging from 0.23.0 through 0.23.11 and all 2.x versions prior to 2.5.2. This issue specifically manifests when Kerberos authentication is enabled within the Hadoop cluster environment, creating a pathway for remote attackers to exploit file permission controls through a sophisticated symlink attack mechanism. The vulnerability exploits the distributed cache functionality within YARN, which is designed to distribute application resources across the cluster for efficient processing.
The technical implementation of this vulnerability stems from improper handling of symbolic links during the file localization process within the NodeManager daemon. When users submit applications that utilize public tar archives containing distributed cache resources, the system fails to properly validate or sanitize symbolic links that may point to sensitive system files or directories. Attackers can construct malicious tar archives containing symlinks that, when processed by the NodeManager during cache localization, result in unintended file permission modifications. This particular flaw falls under the category of CWE-59, which specifically addresses improper handling of symbolic links, and more broadly relates to CWE-276, concerning incorrect permissions for critical resources.
The operational impact of this vulnerability is significant as it allows remote cluster users to escalate their privileges by making sensitive files world-readable, potentially exposing confidential data and system resources to unauthorized access. When the NodeManager processes a maliciously crafted tar archive, the symlink attack can modify permissions of existing files, particularly those within the distributed cache directory structure. This permission modification can lead to information disclosure, as attackers can access files that should normally be restricted to specific user groups or system processes. The vulnerability essentially undermines the security model of the distributed computing environment by allowing arbitrary users to manipulate file access controls.
The attack vector specifically targets the distributed cache mechanism within YARN, where applications can specify resources that should be made available to container processes. During the localization phase, when these resources are extracted and made available to the containers, the system should maintain proper file permissions and prevent malicious file manipulation. However, the vulnerability allows attackers to bypass these security controls through carefully crafted symbolic links that, when dereferenced during the extraction process, modify the permissions of existing files in the system. This attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1078 tactic for Valid Accounts and T1059 for Command and Scripting Interpreter, as it leverages legitimate cluster functionality to achieve unauthorized access.
Mitigation strategies for CVE-2014-3627 require immediate patching of affected Hadoop versions to 2.5.2 or later, where the vulnerability has been addressed through improved symlink handling during the distributed cache localization process. Organizations should implement additional controls such as restricting the use of public tar archives in distributed cache, implementing strict file permission validation, and monitoring for unauthorized permission changes in the NodeManager's cache directories. The fix typically involves enhanced validation of symbolic links during archive extraction, ensuring that any symlinks are properly resolved and that file permissions are maintained according to the security policies of the cluster. System administrators should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities within their distributed computing environments.