The Openwall OSS-Security mailing list post details multiple vulnerabilities discovered in rsync, a widely used utility for file synchronization. These vulnerabilities affect both the server (rsyncd) and client components.
The most critical vulnerability, CVE-2023-23930, is a heap-based buffer overflow in the name_to_gid() function. This flaw allows an authenticated user with write access to a module to trigger the overflow through a specially crafted module name when connecting to an rsync server. Successful exploitation could lead to arbitrary code execution with the privileges of the rsync daemon, typically root. This vulnerability impacts rsync versions 3.2.7 and earlier.
Another vulnerability, CVE-2023-23931, is an integer overflow within the read_varint() function. This vulnerability can lead to a heap-based buffer overflow when handling specially crafted data during the initial handshake between the rsync client and server. This flaw can be triggered by an unauthenticated attacker, allowing potential remote code execution as the user running the rsync daemon. This affects rsync versions 3.2.4 and earlier. Due to specifics in the exploit, it is more easily exploitable on 32-bit architectures. While impacting both client and server, exploitation requires connecting a malicious client to a vulnerable server or a vulnerable client connecting to a malicious server.
A further vulnerability, CVE-2024-0543, allows unauthenticated remote users to cause a denial-of-service (DoS) condition. This is achieved by sending a large number of invalid requests to the rsync server. This DoS vulnerability affects rsync versions from 3.0.0 up to and including 3.7.0. The impact is specifically on the server component, rsyncd. While not as severe as remote code execution, this can disrupt service availability.
Finally, CVE-2024-0545 is a heap out-of-bounds write vulnerability in the rsync client, specifically during the file list transfer phase. An attacker could potentially exploit this by providing a malicious file list, which, when processed by a vulnerable client, could lead to a crash or potentially to arbitrary code execution. This affects versions from 3.0.0 up to and including 3.7.0. Unlike the other vulnerabilities primarily affecting the server, this one targets the client connecting to a potentially malicious server.
In summary, these vulnerabilities range in severity from denial of service to remote code execution. They highlight the importance of updating rsync installations to the latest patched versions to mitigate the risks posed by these flaws. Both client and server components are susceptible, requiring careful consideration of the attack vectors and potential impact on different system architectures.
Summary of Comments ( 8 )
https://news.ycombinator.com/item?id=42706732
Hacker News users discussed the disclosed rsync vulnerabilities, primarily focusing on the practical impact. Several commenters downplayed the severity, noting the limited exploitability due to the requirement of a compromised rsync server or a malicious client connecting to a user's server. Some highlighted the importance of SSH as a secure transport layer, mitigating the risk for most users. The conversation also touched upon the complexities of patching embedded systems and the potential for increased scrutiny of rsync's codebase following these disclosures. A few users expressed concern over the lack of memory safety in C, suggesting it as a contributing factor to such vulnerabilities.
The Hacker News post titled "Rsync vulnerabilities" (https://news.ycombinator.com/item?id=42706732) has several comments discussing the disclosed vulnerabilities in rsync. Many commenters express concern over the severity of these vulnerabilities, particularly CVE-2024-25915, which is described as a heap-based buffer overflow. This vulnerability is seen as potentially serious due to the widespread use of rsync and the possibility of remote code execution.
Several comments highlight the importance of updating rsync installations promptly. One user points out the specific versions affected and emphasizes the need to upgrade to a patched version. Another commenter expresses surprise that rsync, a mature and widely used tool, still contains such vulnerabilities.
A recurring theme in the comments is the complexity of patching rsync, particularly in larger deployments. One user describes the challenge of patching numerous embedded systems running rsync. Another commenter mentions potential disruptions to automated processes and expresses concern about unforeseen consequences.
The discussion also touches on the history of rsync security and the fact that similar vulnerabilities have been found in the past. This leads some commenters to speculate about the underlying causes of these issues and to suggest improvements to the development and auditing processes.
Several users share their experiences with rsync and its alternatives. Some commenters recommend specific tools or approaches for managing file synchronization and backups. Others discuss the trade-offs between security, performance, and ease of use.
Some technical details about the vulnerabilities are also discussed, including the specific conditions required for exploitation and the potential impact on different systems. One commenter explains the concept of heap overflows and the risks associated with them. Another commenter describes the mitigation strategies implemented in the patched versions.
Overall, the comments reflect a mixture of concern, pragmatism, and technical analysis. Many users express the need for vigilance and proactive patching, while also acknowledging the practical challenges involved. The discussion highlights the importance of responsible disclosure and the ongoing efforts to improve the security of widely used software.