A recently discovered security vulnerability, classified under the Common Vulnerabilities and Exposures (CVE) ID CVE-2023-5289, reveals an issue related to insufficient resource allocation controls and throttling within the open-source ikus060/rdiffweb project up to, and including, version 2.8.3. This post aims to provide a high-level overview and key exploit details, as well as available fixes for this vulnerability.

## What is ikus060/rdiffweb?

The ikus060/rdiffweb project is an open-source web interface for browsing and restoring data from an rdiff-backup repository. rdiff-backup is a versatile and robust backup solution that provides efficient incremental backups and restores using a combination of the rsync algorithm (for data compression) and a reverse-delta algorithm (for file comparison). ikus060/rdiffweb simplifies backup management by offering a user-friendly web interface for monitoring the status of backups and managing repositories.

Exploit Details

CVE-2023-5289 is a vulnerability related to the allocation of resources without any imposed limits or control mechanisms, which could potentially be exploited by malicious users to cause a Denial of Service (DoS) attack.

In versions prior to 2.8.4, ikus060/rdiffweb lacked necessary bounds checking and resource control mechanisms to prevent certain operations from consuming excessive amounts of system resources such as CPU and memory. A malicious user could take advantage of this vulnerability to submit requests that would consume a disproportionate amount of system resources, causing a significant degradation in performance and possibly crashing the system.

The following code snippet demonstrates an example of this issue within the affected rdiffweb module

def restore(self):
    # ... omitted for brevity

    # Vulnerable code block
    repos = self.repo_obj_factory.get_repos(user_obj)
    for repo in repos:
        # No resource limit checks or throttling applied here
        repo.restore(target_path, revisions, display_notes)

In the code snippet above, no resource checks or throttling mechanisms are applied when iterating through the repositories and calling the restore method. This can potentially lead to unbounded resource consumption and system performance issues.

Mitigation Measures

The vulnerability has been addressed in ikus060/rdiffweb 2.8.4 and subsequent releases. It is highly recommended to upgrade to the latest version to resolve the issue and avoid potential exploitation.

Specifically, the fix introduces bounds checking and resource control measures to prevent operations from using excessive amounts of system resources. Here's an overview of the changes:

Throttling mechanisms have been added to reduce the load on CPU and memory.

You can further protect your system by following best practices for securing your ikus060/rdiffweb installation, such as regular software updates, strong authentication mechanisms, and network security measures.

Conclusion

In summary, CVE-2023-5289 is a critical security vulnerability in the ikus060/rdiffweb project, which could potentially lead to severe resource exhaustion and degradation of system performance, making it vulnerable to DoS attacks. It is strongly recommended that users ensure they are running an updated version of ikus060/rdiffweb, specifically version 2.8.4 or later, in order to mitigate the risk of exploitation.

Timeline

Published on: 09/29/2023 14:15:00 UTC
Last modified on: 10/02/2023 18:13:00 UTC