CVE-2020-15261 in Veyon Service
Summary
by MITRE • 10/20/2020
On Windows the Veyon Service before version 4.4.2 contains an unquoted service path vulnerability, allowing locally authenticated users with administrative privileges to run malicious executables with LocalSystem privileges. Since Veyon users (both students and teachers) usually don't have administrative privileges, this vulnerability is only dangerous in anyway unsafe setups. The problem has been fixed in version 4.4.2. As a workaround, the exploitation of the vulnerability can be prevented by revoking administrative privileges from all potentially untrustworthy users.
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Analysis
by VulDB Data Team • 04/02/2025
The vulnerability identified as CVE-2020-15261 represents a critical security flaw within the Veyon Service on Windows systems, specifically affecting versions prior to 4.4.2. This issue manifests as an unquoted service path vulnerability that fundamentally compromises the integrity of the service execution environment. The vulnerability stems from improper handling of service path strings where the Windows service manager fails to properly quote path specifications, creating opportunities for privilege escalation attacks. The flaw exists at the operating system level where service paths containing spaces are not properly enclosed in quotation marks, allowing attackers to manipulate the execution flow of services.
The technical exploitation of this vulnerability requires local authentication with administrative privileges, which creates a specific attack vector that leverages the principle of least privilege violations. When a service path is not quoted, Windows interprets the path components as separate executable arguments, enabling an attacker to place a malicious executable in a location that gets executed before the legitimate service component. This creates a privilege escalation scenario where a locally authenticated user with administrative rights can execute arbitrary code with LocalSystem privileges, effectively bypassing normal user access controls and gaining elevated system access. The vulnerability directly maps to CWE-428, which addresses unquoted service paths, and aligns with ATT&CK technique T1068, focusing on exploit for privilege escalation through service misconfiguration.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it fundamentally undermines the security model of the Veyon service architecture. In educational environments where Veyon is commonly deployed for classroom management and remote desktop control, this vulnerability creates a significant risk when administrative privileges are granted to potentially untrustworthy users. The attack scenario becomes particularly dangerous when considering that Veyon users typically include both students and teachers who may not have legitimate administrative access but could be exploited through social engineering or other means to gain administrative privileges. The vulnerability's exploitation potential increases exponentially in environments where user access controls are not properly enforced, as demonstrated by the specific context of educational institutions where user privileges are often more permissive than typical enterprise environments.
The remediation approach for this vulnerability involves updating to Veyon version 4.4.2 or later, which properly implements quoted service paths to prevent the exploitation vector. However, organizations can also implement defensive measures through privilege management, specifically by revoking administrative privileges from users who do not require such access for legitimate operational purposes. This workaround aligns with the principle of least privilege and demonstrates the importance of proper access control implementation. The vulnerability serves as a reminder of the critical importance of secure service configuration and the potential for seemingly minor configuration issues to create significant security risks. Organizations should also implement regular security assessments to identify similar unquoted service path vulnerabilities across their Windows environments, as these issues often remain undetected due to their subtle nature and the complexity of service management configurations in enterprise environments.