Critical Vulnerability in rsync: Access Restriction Bypass
Summary
ALPINE-CVE-2017-17433: The recv_files function in receiver.c in the daemon in rsync 3.1.2, and 3.1.3-development before 2017-12-03, proceeds with certain file metadata updates before checking for a filename in the daemon_filter_list data struc... Affects rsync versions < 3.1.2-r7. Fixed in 3.1.2-r7. How to fix ↓
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Background
rsync is a widely used utility for efficiently transferring and synchronizing files across computer systems. It is known for its speed and flexibility, allowing users to copy files locally and remotely while minimizing data transfer by only sending the differences between source and destination files. However, certain versions of rsync are vulnerable to a flaw that can allow unauthorized access to files, undermining its security features.
Vulnerability Detail
The vulnerability, identified as CVE-2017-17433, arises from the recv_files function in the rsync daemon. This function updates file metadata before verifying the filename against the daemon_filter_list, which is intended to restrict access. As a result, remote attackers can exploit this flaw to bypass access restrictions, potentially leading to unauthorized file access and data exposure. The vulnerability affects rsync versions 3.1.2 and 3.1.3-development prior to December 3, 2017.
How To Fix
Minimum fixed version
3.1.2-r7
This is the first release that contains the fix.
sudo apk add --upgrade rsyncTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, consider restricting access to the rsync daemon by implementing firewall rules or using SSH tunneling to limit exposure until the package can be updated.
Conclusion
The CVE-2017-17433 vulnerability in rsync poses a significant risk by allowing unauthorized access to files. It is crucial for users to update to the patched versions of rsync to mitigate this risk. Utilizing tools like Vulert can help monitor and alert for such vulnerabilities in real-time.
See every vulnerability recorded for rsync →
FAQ
CVE-2017-17433 is a vulnerability in rsync that allows remote attackers to bypass access restrictions due to improper handling of file metadata updates.
The vulnerability affects rsync versions 3.1.2 and 3.1.3-development prior to December 3, 2017.
You can use Vulert, which monitors open-source vulnerabilities in your software. Check your application against this vulnerability using the Vulert playground at Vulert Scanner.
The CVSS score for this vulnerability is 3.7, indicating a moderate severity level.
If immediate updates are not possible, consider implementing firewall rules or SSH tunneling to restrict access to the rsync daemon as a temporary measure.
References
Related vulnerabilities
Recent vulnerabilities recorded for rsync.
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