CVE-2019-14743 in Steam Client
Summary
by MITRE
** DISPUTED ** In Valve Steam Client for Windows through 2019-08-07, HKLM\SOFTWARE\Wow6432Node\Valve\Steam has explicit "Full control" for the Users group, which allows local users to gain NT AUTHORITY\SYSTEM access. NOTE: the vendor disputes the significance of this finding; the discoverer was reportedly told that the Steam threat model excludes "Attacks that require physical access to the user's device" and "Attacks that require the ability to drop files in arbitrary locations on the user's filesystem" (which might apply to the attacker's ability to create links under HKLM\SOFTWARE\Wow6432Node\Valve\Steam\Apps).
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/21/2023
The vulnerability described in CVE-2019-14743 pertains to the Valve Steam Client for Windows, specifically addressing a privilege escalation issue that could potentially allow local users to achieve system-level access. This flaw exists within the Windows registry configuration where the HKLM\SOFTWARE\Wow6432Node\Valve\Steam registry key is configured with explicit "Full control" permissions for the Users group. The registry path represents a critical system location where Steam client configuration data is stored, and the overly permissive access control settings create a security weakness that could be exploited by malicious actors with local access to the system.
This vulnerability represents a classic example of improper access control within Windows registry structures, which aligns with CWE-276, "Insecure Default Permissions." The registry key in question is part of the Windows 64-bit registry view that handles 32-bit application data, specifically designed to support Steam's operation across different system architectures. When the Users group is granted full control over this registry location, it creates a pathway for privilege escalation attacks that bypass normal Windows security boundaries. The issue is particularly concerning because it allows a local user to potentially gain access to NT AUTHORITY\SYSTEM privileges, which represents the highest level of system access in Windows environments.
From an operational perspective, the impact of this vulnerability is significant despite the vendor's assertion that it does not represent a serious security concern. The flaw demonstrates how seemingly minor configuration issues in application deployment can create substantial security risks. The vulnerability requires local access to the target system, which means an attacker must already have physical or remote access to the device to exploit it. However, once exploited, the privilege escalation could enable attackers to perform actions such as installing malicious software, modifying system files, creating new user accounts, or accessing sensitive data that would normally be protected from standard user accounts.
The security implications extend beyond simple privilege escalation, as this vulnerability could potentially be combined with other attack vectors to create more sophisticated exploitation scenarios. The vendor's stated threat model exclusion of attacks requiring physical access or file dropping capabilities suggests that Steam's security architecture assumes a certain level of physical security and user trust. This approach aligns with the concept of security through obscurity and implicit trust models that are common in client applications. However, the vulnerability demonstrates that even applications with such assumptions can contain flaws that undermine their security posture when combined with other exploitation techniques.
The recommended mitigation strategies for this vulnerability should focus on proper registry configuration management and access control enforcement. System administrators should review registry permissions for all application-specific keys and ensure that only necessary users or groups have appropriate access levels. The principle of least privilege should be strictly enforced, and registry keys should not grant unnecessary permissions to the Users group or other broad access control entities. Additionally, regular security audits should be conducted to identify and remediate similar issues in other applications and system components. The vulnerability serves as a reminder of the importance of proper access control implementation in Windows environments and the potential consequences of overly permissive security configurations.