CVE-2021-35949 : Exploit Details and Defense Strategies

The shareinfo controller in the ownCloud Server before 10.8.0 allows an attacker to bypass the permission checks for upload only shares and list metadata about the share.

Understanding CVE-2021-35949

This CVE identifies a vulnerability in the shareinfo controller in ownCloud Server that enables an attacker to circumvent permission checks on upload-only shares.

What is CVE-2021-35949?

The shareinfo controller in ownCloud Server version prior to 10.8.0 is susceptible to exploitation by malicious actors to surpass permission controls on sharing files and view metadata.

The Impact of CVE-2021-35949

The vulnerability allows unauthorized individuals to access additional information and potentially compromise the confidentiality and integrity of shared data within the ownCloud Server environment.

Technical Details of CVE-2021-35949

The specific technical details include:

Vulnerability Description

The flaw in the shareinfo controller permits attackers to evade upload-only share permission restrictions and gather share metadata.

Affected Systems and Versions

All ownCloud Server installations before version 10.8.0 are affected by this vulnerability.

Exploitation Mechanism

Exploitation involves leveraging the shareinfo controller loophole to view share metadata without proper permission validation.

Mitigation and Prevention

To address CVE-2021-35949, consider the following measures:

Immediate Steps to Take

Update ownCloud Server to version 10.8.0 or later to eliminate the vulnerability.
Monitor and audit sharing activities to detect unauthorized access.

Long-Term Security Practices

Regularly update and patch ownCloud Server to prevent known vulnerabilities.
Conduct security training to educate users on safe sharing practices.

Patching and Updates

Ensure timely application of security patches from ownCloud, especially for critical vulnerabilities like CVE-2021-35949.