CVE-2014-9512 in rsync
Summary
by MITRE
rsync 3.1.1 allows remote attackers to write to arbitrary files via a symlink attack on a file in the synchronization path.
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Analysis
by VulDB Data Team • 07/01/2018
The vulnerability identified as CVE-2014-9512 affects rsync version 3.1.1 and represents a significant security flaw that enables remote attackers to manipulate file system operations through symbolic link manipulation. This issue arises from the improper handling of symbolic links during the synchronization process, creating a path traversal condition that can be exploited to write data to unintended locations on the target system. The vulnerability specifically manifests when rsync processes files in a synchronization path that contains symbolic links, allowing an attacker to manipulate the target of these links to redirect file operations to arbitrary locations.
The technical root cause of this vulnerability lies in the way rsync handles file system operations when symbolic links are present in the synchronization path. During the synchronization process, rsync performs file operations that do not adequately resolve or validate symbolic links before executing write operations. This behavior creates a window where an attacker can craft a scenario where a symbolic link points to a location outside the intended synchronization scope, enabling the attacker to write files to arbitrary locations on the target system. The flaw is classified under CWE-59 as improper link resolution, which is a well-documented weakness in file system access controls.
From an operational perspective, this vulnerability poses a severe risk to systems running rsync 3.1.1, particularly those configured to allow remote synchronization operations. Attackers can exploit this flaw to overwrite critical system files, inject malicious content into sensitive directories, or establish persistent access points through the manipulation of symbolic links in synchronization paths. The impact extends beyond simple file corruption as it can enable privilege escalation scenarios where attackers gain write access to protected system areas. This vulnerability directly maps to ATT&CK technique T1059.007 for execution through remote services and T1078.004 for valid accounts, as it leverages legitimate synchronization operations to achieve malicious file system modifications.
The exploitation of this vulnerability requires the attacker to have network access to the rsync service and knowledge of the synchronization path structure to create the appropriate symbolic link manipulation. The attack vector is particularly dangerous because it can be executed without requiring authentication for the synchronization process itself, making it accessible to remote attackers. Organizations using rsync in production environments should consider immediate mitigation strategies, including updating to rsync versions that address this vulnerability, implementing proper file system access controls, and monitoring synchronization operations for suspicious symbolic link usage patterns. The vulnerability demonstrates the importance of proper input validation and file system operation handling in network services, aligning with security principles outlined in the OWASP Top Ten and NIST Cybersecurity Framework.