CVE-2021-37617 : Vulnerability Insights and Analysis

A critical vulnerability, CVE-2021-37617, has been identified in the Nextcloud Desktop Client versions 3.0.3 through 3.2.4. This vulnerability could allow a malicious user to execute arbitrary code with administrative privileges. Here is all you need to know about this security issue.

Understanding CVE-2021-20657

Nextcloud Desktop Client versions 3.0.3 through 3.2.4 are affected by an Untrusted Search Path vulnerability.

What is CVE-2021-20657?

The Nextcloud Desktop Client can be manipulated by a malicious user to execute a specially crafted

Uninstall.exe

file with elevated privileges during the installation process, leading to a security breach.

The Impact of CVE-2021-20657

The vulnerability has a high severity impact, with a CVSS base score of 7.3. It can result in unauthorized access, data confidentiality breaches, and integrity compromises, posing a significant security risk to affected systems.

Technical Details of CVE-2021-20657

The following technical details outline the specifics of the vulnerability:

Vulnerability Description

In versions 3.0.3 through 3.2.4, the Nextcloud Desktop Client searches for the

Uninstall.exe

file in a directory that is writable by regular users. This behavior can be exploited by an attacker to run a malicious

Uninstall.exe

with elevated privileges.

Affected Systems and Versions

The vulnerability affects Nextcloud Desktop Client versions 3.0.3 through 3.2.4.

Exploitation Mechanism

An attacker can create a specially crafted

Uninstall.exe

file in the accessible directory to trigger its execution during the client's installation, leading to potential privilege escalation.

Mitigation and Prevention

To secure your Nextcloud Desktop Client installation and mitigate the risks associated with CVE-2021-20657, consider the following steps:

Immediate Steps to Take

Upgrade to Nextcloud Desktop Client version 3.3.0 or newer, which includes a fix for this vulnerability.
Restrict untrusted users from creating content in critical system directories.
Ensure there are no malicious

Uninstall.exe

files present in sensitive folders.

Long-Term Security Practices

Regularly update your Nextcloud Desktop Client to the latest version to patch known security vulnerabilities.
Implement strict access controls and permissions to prevent unauthorized access to critical system files.

Patching and Updates

Stay informed about security advisories and patches released by Nextcloud to address potential security vulnerabilities in the Desktop Client.