CVE-2015-0941 in Inetc
Summary
by MITRE
The Inetc plugin for Nullsoft Scriptable Install System (NSIS), as used in CERT/CC Failure Observation Engine (FOE) and other products, does not verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and possibly execute arbitrary code by sending a crafted certificate in a download session for Windows executable files.
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Analysis
by VulDB Data Team • 11/04/2024
The vulnerability identified as CVE-2015-0941 affects the Inetc plugin within Nullsoft Scriptable Install System NSIS, a widely used tool for creating Windows installers. This flaw specifically targets the certificate verification process during SSL connections, creating a critical security gap that enables sophisticated man-in-the-middle attacks. The vulnerability manifests in products including CERT/CC Failure Observation Engine (FOE) and numerous other applications that leverage NSIS for their installation processes, making it a widespread concern across multiple software ecosystems. The flaw stems from the plugin's failure to properly validate X.509 certificates, which are fundamental to establishing secure communications over the internet.
The technical implementation of this vulnerability involves the Inetc plugin's improper handling of SSL certificate validation during download operations. When the plugin attempts to download Windows executable files from remote servers, it fails to perform essential certificate checks that would normally verify the server's identity and ensure the connection's integrity. This allows attackers to present fraudulent certificates that appear legitimate to the plugin, effectively bypassing the security mechanisms designed to protect users from malicious actors. The vulnerability operates at the transport layer security level, specifically targeting the SSL/TLS certificate validation process that should normally prevent unauthorized parties from impersonating legitimate servers.
The operational impact of this vulnerability extends beyond simple certificate validation failures, creating potential pathways for arbitrary code execution and complete system compromise. Attackers can exploit this weakness by intercepting network traffic between vulnerable applications and their intended servers, presenting forged certificates that the plugin accepts without proper verification. This enables attackers to serve malicious executable files disguised as legitimate software updates or downloads, potentially leading to full system compromise. The vulnerability particularly affects Windows executable files, making it especially dangerous for software installation processes where users expect to download and execute trusted applications. This flaw represents a significant departure from standard security practices and violates fundamental principles of secure communication protocols.
Security professionals should recognize this vulnerability as a direct violation of established security standards including those outlined in CWE-295, which addresses improper certificate validation, and aligns with ATT&CK techniques related to credential access and execution through malicious downloads. The vulnerability demonstrates a critical failure in the principle of least privilege and secure communication, where the absence of proper certificate verification creates an attack surface that can be exploited to gain unauthorized access to systems. Organizations should immediately implement mitigations including updating to patched versions of NSIS and related products, implementing network monitoring to detect suspicious certificate behavior, and ensuring that all SSL/TLS connections perform proper certificate validation. Additionally, administrators should consider implementing additional security layers such as network segmentation and application whitelisting to reduce the potential impact of successful exploitation attempts.