CVE-2015-2371 in Windows
Summary
by MITRE
The Windows Installer service in Microsoft Windows Server 2003 SP2 and R2 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows local users to gain privileges via a custom action script associated with a .msi package, aka "Windows Installer EoP Vulnerability."
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-2015-2371 represents a critical privilege escalation flaw within the Windows Installer service that affects multiple versions of Microsoft Windows operating systems. This vulnerability specifically targets the Windows Installer service component that processes .msi package files, creating an avenue for local attackers to elevate their system privileges from standard user level to administrative rights. The flaw exists in the way the installer service handles custom action scripts embedded within malicious or compromised installation packages, allowing unauthorized code execution with elevated privileges. This issue is particularly concerning because it leverages legitimate system components to achieve unauthorized privilege escalation, making detection and prevention more challenging for security professionals.
The technical implementation of this vulnerability stems from insufficient validation of custom action scripts within Windows Installer packages. When a user or process executes an .msi file containing malicious custom actions, the Windows Installer service fails to properly validate the execution context and privilege levels associated with these scripts. This weakness enables attackers to craft specially designed installation packages that, when executed, can run arbitrary code with elevated privileges. The vulnerability is classified under CWE-787 as an out-of-bounds write, though more specifically relates to improper privilege handling within the installer service. According to ATT&CK framework, this represents a privilege escalation technique using legitimate system tools and services, specifically mapping to T1068 which covers "Local Privilege Escalation" through the exploitation of service vulnerabilities.
The operational impact of CVE-2015-2371 extends beyond simple privilege escalation, as it can serve as a foundational attack vector for more sophisticated compromise techniques. Once an attacker gains elevated privileges through this vulnerability, they can manipulate system files, install additional malware, modify registry settings, and establish persistence mechanisms within the compromised system. The vulnerability affects both 32-bit and 64-bit versions of affected operating systems, including legacy systems that may still be in production environments, making it particularly dangerous for organizations with older infrastructure. The attack surface is broad as any user with the ability to execute .msi installation packages can potentially exploit this vulnerability, whether through social engineering, phishing attacks, or by compromising legitimate software distribution channels. This vulnerability also aligns with ATT&CK's T1547.001 which covers "Registry Run Keys / Startup Folder" persistence techniques, as attackers can use elevated privileges to establish malicious persistence mechanisms.
Mitigation strategies for CVE-2015-2371 should focus on both immediate patching and operational security improvements. Microsoft released security updates in May 2015 that addressed this vulnerability through enhanced validation of custom action scripts and improved privilege handling within the Windows Installer service. Organizations should prioritize applying these patches across all affected systems, particularly those running older versions of Windows that may not receive extended support. Additional protective measures include implementing application whitelisting policies that restrict execution of .msi files from untrusted sources, monitoring for unusual installer service activity, and enforcing least privilege principles to limit user capabilities. Network segmentation and endpoint protection solutions can help detect and prevent exploitation attempts, while regular security assessments should verify that no systems remain vulnerable to this attack vector. The vulnerability also underscores the importance of maintaining current security practices, as the exploitation techniques used in this case represent common attack patterns that have been documented in various threat actor toolkits and exploit frameworks.