CVE-2021-42110 is a high-severity vulnerability affecting Allegro Windows (formerly known as Popsy Windows) versions prior to 3.3.4156.1. The vulnerability arises due to DLL hijacking within the FTP module of the software. Specifically, a standard user on a system where the vulnerable Allegro Windows FTP module is installed can escalate their privileges to SYSTEM level. DLL hijacking occurs when an application loads a dynamic link library (DLL) from an untrusted or user-writable directory, allowing an attacker to substitute a malicious DLL that the application will load and execute with elevated privileges. In this case, the FTP module's improper handling of DLL loading paths enables a local attacker without prior privileges (no authentication required) to execute arbitrary code with SYSTEM privileges, the highest level on Windows systems. The CVSS v3.1 score of 7.1 reflects a high severity, with the vector indicating low attack complexity (AC:L), requiring local access (AV:A), no user interaction (UI:N), no privileges required (PR:N), and impacting confidentiality highly (C:H) with limited impact on integrity (I:L) and no impact on availability (A:N). No known exploits in the wild have been reported, but the vulnerability presents a significant risk if exploited. The lack of vendor and product details limits the ability to identify exact affected deployments, but the presence of the FTP module is a prerequisite for exploitation.

For European organizations, this vulnerability poses a serious threat, especially in environments where Allegro Windows is used with the FTP module enabled. Successful exploitation allows an attacker with standard user access to gain SYSTEM-level privileges, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, disruption of critical services, and the ability to deploy further malware or ransomware. Given the high confidentiality impact, sensitive corporate or personal data could be exposed or exfiltrated. The vulnerability is particularly concerning in sectors with strict data protection requirements such as finance, healthcare, and government institutions across Europe. Additionally, organizations with remote or multi-user access environments are at increased risk since local access is required but no additional privileges or user interaction are needed. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, as attackers may develop exploits over time.

To mitigate this vulnerability, European organizations should first identify all instances of Allegro Windows deployed within their environments, specifically verifying if the FTP module is installed and active. Immediate steps include applying any available patches or updates from the software vendor; if no patches are currently available, organizations should consider disabling the FTP module to eliminate the attack vector. Implement strict access controls to limit standard user access on systems running Allegro Windows, reducing the risk of local exploitation. Employ application whitelisting and monitor for unauthorized DLL loading or suspicious DLL files in directories used by Allegro Windows. Conduct regular integrity checks on DLL files associated with the FTP module. Additionally, enhance endpoint detection and response (EDR) capabilities to detect privilege escalation attempts and anomalous process behaviors. Network segmentation can limit lateral movement if compromise occurs. Finally, maintain up-to-date backups and incident response plans to quickly recover from potential exploitation.