CVE-2011-1097 in rsync
Summary
by MITRE
rsync 3.x before 3.0.8, when certain recursion, deletion, and ownership options are used, allows remote rsync servers to cause a denial of service (heap memory corruption and application crash) or possibly execute arbitrary code via malformed data.
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Analysis
by VulDB Data Team • 01/15/2025
The vulnerability identified as CVE-2011-1097 represents a critical security flaw in rsync versions 3.x prior to 3.0.8 that manifests through improper handling of recursive operations, file deletion commands, and ownership modifications. This vulnerability exposes remote rsync servers to potential exploitation where maliciously crafted data can trigger heap memory corruption leading to application crashes or unauthorized code execution. The flaw specifically occurs when rsync processes certain combinations of recursive directory traversal, deletion operations, and ownership change commands, creating a scenario where attacker-controlled data can manipulate the memory management functions of the rsync daemon.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the rsync protocol handler. When the rsync server receives data containing malformed recursive structures or improper deletion sequences combined with ownership modifications, the internal heap allocation and deallocation routines become corrupted. This memory corruption occurs because the software fails to properly sanitize or validate the data structures that define recursive operations, deletion targets, and ownership specifications before processing them. The vulnerability operates at the protocol level where rsync's daemon processes incoming data streams and translates them into memory operations, making it particularly dangerous as it can be triggered through normal network communication without requiring authentication or special privileges.
From an operational perspective, this vulnerability creates significant risks for systems running vulnerable rsync versions, particularly in environments where rsync servers are exposed to untrusted networks or users. The potential for remote code execution means that attackers could gain control over systems running vulnerable rsync daemons, potentially leading to complete system compromise. The denial of service aspect alone can cause service disruption affecting legitimate users and business operations, while the arbitrary code execution capability allows for persistent backdoor installation, data exfiltration, or further network exploitation. Organizations using rsync for file synchronization, backup operations, or remote file management are particularly at risk since these systems often operate continuously and may be accessible from multiple network locations.
The impact of this vulnerability aligns with CWE-121, which addresses heap-based buffer overflow conditions, and can be mapped to ATT&CK technique T1059 for remote code execution through network services. The vulnerability specifically targets the memory management components of rsync, making it a prime candidate for exploitation through carefully crafted network packets that manipulate the recursive file transfer protocols. Security professionals should note that this vulnerability demonstrates the importance of input validation in network services and the potential for memory corruption attacks to escalate from simple denial of service to full system compromise. Organizations should implement immediate patching of rsync installations to version 3.0.8 or later, while also monitoring network traffic for signs of exploitation attempts.
Mitigation strategies for CVE-2011-1097 should include immediate deployment of the official rsync patches available from the project maintainers, along with network segmentation to limit exposure of rsync services to untrusted networks. System administrators should also implement monitoring solutions to detect unusual rsync activity patterns and establish regular vulnerability scanning procedures to identify other potentially affected systems. The vulnerability serves as a reminder of the critical importance of keeping network services updated and maintaining proper input validation mechanisms in protocol implementations. Additionally, organizations should consider implementing network access controls that restrict rsync daemon access to trusted IP addresses and establish logging mechanisms to track rsync operations for security analysis purposes.