CVE-2026-107782 in System Informer
Summary
by MITRE • 10/09/2026
System Informer before 4.0.26241.138 contains an incorrect authorization vulnerability in the phsvc helper that allows local attackers to reach privileged APIs by connecting from any Authenticode-signed process. Attackers can load code into a Microsoft-signed host like rundll32.exe, connect to SiSvcApiPort, and call PhSvcApiCreateService to execute code as SYSTEM.
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Analysis
by VulDB Data Team • 10/09/2026
System Informer prior to version 4.0.26241.138 contains a critical authorization bypass vulnerability within its phsvc helper component that enables local privilege escalation from an unprivileged user context to the highly privileged SYSTEM account. This flaw stems from an incorrect implementation of access control checks, specifically failing to validate the identity or trust level of the client process attempting to communicate with the service's named pipe endpoint. Instead of verifying whether the calling application possesses legitimate administrative privileges or a specific security token required for such operations, the system relies on a flawed logic that accepts connections originating from any process signed by Authenticode. This design oversight effectively treats all digitally signed executables as trusted entities capable of invoking sensitive management functions, regardless of their actual intent or the user context under which they are running.
The technical mechanism of this exploitation involves an attacker crafting a malicious application that is properly code-signed using a valid certificate. By leveraging common Windows utilities such as rundll32.exe, which is inherently Microsoft-signed and thus trusted by the flawed authorization logic, an adversary can load their custom payload into the host process memory space. Once loaded, the injected code establishes a connection to the SiSvcApiPort named pipe associated with System Informer's phsvc service. Through this established channel, the attacker invokes the PhSvcApiCreateService API function. Because the system incorrectly authorizes any Authenticode-signed caller, it grants the request without verifying if the underlying user has the necessary permissions to create services or execute code at a higher privilege level. Consequently, the requested operation is executed with SYSTEM-level privileges, effectively bypassing standard Windows security boundaries and access control lists that would normally prevent such actions from unprivileged accounts.
The operational impact of this vulnerability is severe, as it allows for direct local privilege escalation without requiring any additional software installation or complex exploitation techniques beyond code signing capabilities. An attacker who gains even basic user-level access to a vulnerable system can leverage this flaw to execute arbitrary commands with the highest level of authority available on Windows systems. This capability facilitates comprehensive system compromise, including the ability to install persistent backdoors, modify critical system configurations, steal sensitive data protected by administrative restrictions, and disable security monitoring tools. The reliance on code signing as a sole authorization mechanism is particularly dangerous because legitimate software often maintains valid signatures for years, providing attackers with a wide attack surface of trusted executables that can be repurposed to facilitate the exploit.
This vulnerability aligns closely with CWE-269, which describes Improper Privilege Management, specifically where an actor obtains elevated privileges without proper authorization checks. Furthermore, it maps directly to MITRE ATT&CK technique T1055.008, Process Injection via DLL side-loading or injection into a signed process, and T1548.003, Abuse Elevation Control Mechanism by exploiting misconfigured access controls. To mitigate this risk, organizations must immediately update System Informer to version 4.0.26241.138 or later, where the authorization logic has been corrected to enforce strict privilege verification for all API calls regardless of code signature status. Additionally, administrators should apply principle of least privilege by restricting access to named pipes used by system services and monitoring for unusual process injection activities involving signed host processes like rundll32.exe. Regular auditing of service creation events and enforcing application control policies can further reduce the likelihood of successful exploitation in environments where such tools might be present or installed.