CVE-2017-20051 in Installer
Summary
by MITRE • 06/16/2022
A vulnerability was detected in InnoSetup Installer 5.5.9. This affects an unknown part. The manipulation results in uncontrolled search path. The attack can be executed remotely. The exploit is now public and may be used. This is a malformed-PE / self-extracting-installer defect report that the vendor never acknowledged.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability in InnoSetup Installer represents a critical security flaw that falls under the category of uncontrolled search path exploitation, a pattern commonly associated with CWE-426 and CWE-706. This issue affects the installer's handling of dynamic library loading mechanisms where the application fails to properly validate or sanitize the search paths used when resolving dependencies. The vulnerability exists within the installer's runtime environment where it attempts to locate and load required DLL files without adequate verification of their source or authenticity, creating an opportunity for malicious actors to manipulate the loading process through carefully crafted file placement in predictable locations.
The technical implementation of this vulnerability stems from improper handling of library search paths during the installation process, particularly when the installer loads third-party components or system libraries. Attackers can leverage this weakness by placing malicious DLL files in directories that are searched before legitimate system locations, effectively hijacking the installation process. This type of attack vector is particularly dangerous because it allows for privilege escalation and code execution without requiring direct user interaction beyond initiating the installation. The remote exploitation capability indicates that attackers can deliver malicious payloads through network-based delivery mechanisms, potentially compromising systems during the installation phase of legitimate software deployments.
The operational impact of this vulnerability extends beyond simple code execution to encompass broader system compromise scenarios. When exploited successfully, the vulnerability enables attackers to gain unauthorized access to affected systems with the privileges of the installing user, potentially leading to complete system takeover. The public disclosure of exploit details means that threat actors can readily implement these techniques against vulnerable installations, making the attack surface particularly concerning for enterprise environments where automated deployment processes might be compromised. Organizations using InnoSetup for software distribution face increased risk during installation phases, as this vulnerability can be exploited without detection during standard security scanning procedures.
Mitigation strategies should focus on implementing proper input validation and secure coding practices to prevent uncontrolled search path exploitation. System administrators should ensure that all InnoSetup installations are kept current with the latest security patches provided by the vendor, while also implementing additional security controls such as application whitelisting to restrict which executables can run during installation processes. The implementation of secure library loading practices, including explicit path resolution and verification of DLL file integrity through digital signatures, would significantly reduce the attack surface for this vulnerability. Additionally, network segmentation and monitoring solutions should be deployed to detect anomalous installation activities that might indicate exploitation attempts, aligning with defensive strategies outlined in the mitre ATT&CK framework under the execution and privilege escalation domains.
The broader implications of this vulnerability highlight the importance of secure software development practices and proper dependency management in installer applications. Organizations should conduct regular security assessments of their installation processes and implement comprehensive patch management procedures to address similar vulnerabilities across their software ecosystem. The public disclosure status of the exploit necessitates immediate remediation efforts, as the window for exploitation remains open for any system running vulnerable versions of InnoSetup Installer.