CVE-2024-23692 is a critical security vulnerability identified in Rejetto HTTP File Server (HFS) versions up to and including 2.3m. The vulnerability is classified under CWE-1336, which involves improper neutralization of special elements used in a template engine. Specifically, the template engine in HFS fails to adequately sanitize or neutralize user-supplied input embedded within templates, allowing an attacker to inject malicious template code. This flaw enables remote attackers to execute arbitrary system commands on the affected server by crafting and sending specially formed HTTP requests without requiring any authentication or user interaction. The vulnerability is particularly severe because it directly compromises the confidentiality, integrity, and availability of the server and its data. The CVSS v3.1 base score of 9.8 reflects the vulnerability's critical nature, with attack vector being network-based, low attack complexity, no privileges required, and no user interaction needed. The affected product, Rejetto HFS 2.3m, is no longer supported, meaning no official patches or updates are available to remediate the issue. This increases the risk for organizations still running this software, as attackers can exploit the vulnerability to gain full control over the server, potentially leading to data theft, server manipulation, or use as a pivot point for further network compromise. No known exploits are publicly reported at the time of disclosure, but the vulnerability's characteristics make it a prime candidate for rapid weaponization. The lack of vendor support necessitates alternative mitigation strategies such as network segmentation, firewall rules, or replacement of the vulnerable software.

For European organizations, the impact of CVE-2024-23692 can be severe. Organizations using Rejetto HFS 2.3m, particularly those exposing the service to the internet or untrusted networks, face a high risk of remote code execution attacks. Successful exploitation can lead to full system compromise, data breaches involving sensitive or personal data protected under GDPR, disruption of business operations due to server downtime, and potential lateral movement within corporate networks. Small and medium enterprises (SMEs) and public sector entities that rely on legacy or lightweight file sharing solutions may be disproportionately affected due to limited IT resources for rapid remediation or migration. The unsupported status of the software complicates incident response and recovery, increasing the likelihood of prolonged exposure. Additionally, compromised servers could be leveraged for launching further attacks, including ransomware or supply chain compromises, amplifying the threat landscape for European organizations.

Given the absence of official patches for Rejetto HFS 2.3m, European organizations should prioritize the following mitigation measures: 1) Immediately identify and inventory all instances of Rejetto HFS in their environment, focusing on internet-facing and critical internal servers. 2) Disable or isolate vulnerable HFS servers from untrusted networks to prevent external exploitation. 3) Deploy web application firewalls (WAFs) with custom rules designed to detect and block malicious template injection payloads targeting HFS. 4) Replace Rejetto HFS with actively supported and secure file sharing solutions that receive regular security updates. 5) Monitor network traffic and server logs for unusual activity indicative of exploitation attempts, such as unexpected command execution or anomalous HTTP requests. 6) Implement network segmentation to limit the potential lateral movement from compromised HFS servers. 7) Educate IT and security teams about the risks associated with unsupported software and the importance of timely software lifecycle management. 8) Consider deploying intrusion detection/prevention systems (IDS/IPS) signatures tailored to this vulnerability once available. These steps collectively reduce the attack surface and improve detection and response capabilities.