CVE-2021-28096 Explained : Impact and Mitigation

The CVE-2021-28096 vulnerability was discovered in Stormshield SNS before version 4.2.3 when the proxy is in use. This vulnerability allows an attacker to saturate the proxy connection table, leading to denial of new connections.

Understanding CVE-2021-28096

This section elaborates on the details and impact of the CVE-2021-28096 vulnerability.

What is CVE-2021-28096?

The CVE-2021-28096 vulnerability exists in Stormshield SNS before version 4.2.3, specifically when the proxy functionality is employed. It enables an attacker to flood the proxy connection table, causing the proxy to reject any new connection attempts.

The Impact of CVE-2021-28096

Exploitation of this vulnerability can result in a denial of service (DoS) condition where legitimate users are unable to establish connections through the affected proxy server.

Technical Details of CVE-2021-28096

In this section, we delve into the specific technical aspects of the CVE-2021-28096 vulnerability.

Vulnerability Description

The vulnerability allows attackers to overwhelm the proxy connection table, rendering the proxy incapable of accepting new connections, thereby disrupting normal network operation.

Affected Systems and Versions

Stormshield SNS versions prior to 4.2.3 are impacted by this vulnerability, particularly when the proxy feature is active.

Exploitation Mechanism

By flooding the proxy connection table, threat actors can exhaust the available resources, leading to a bottleneck that prevents new connections from being established.

Mitigation and Prevention

To mitigate the risks associated with CVE-2021-28096, users are advised to take the following precautionary measures.

Immediate Steps to Take

Update Stormshield SNS to version 4.2.3 or later to eliminate the vulnerability.
Implement network monitoring to detect any abnormal spikes in proxy connection usage.

Long-Term Security Practices

Regularly monitor and audit proxy connection activity to identify any anomalous patterns.
Educate users about safe browsing practices and potential risks associated with DoS attacks.

Patching and Updates

Stay informed about security advisories from Stormshield and promptly apply any patches or updates released to address known vulnerabilities.