CVE-2015-2479 in .NET Framework
Summary
by MITRE
The RyuJIT compiler in Microsoft .NET Framework 4.6 produces incorrect code during an attempt at optimization, which allows remote attackers to execute arbitrary code via a crafted .NET application, aka "RyuJIT Optimization Elevation of Privilege Vulnerability," a different vulnerability than CVE-2015-2480 and CVE-2015-2481.
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Analysis
by VulDB Data Team • 06/09/2022
The RyuJIT compiler vulnerability represents a critical security flaw in Microsoft's .NET Framework 4.6 that manifests during code optimization processes. This vulnerability specifically affects the RyuJIT compiler component responsible for generating optimized machine code from intermediate language instructions. The flaw occurs when the compiler attempts to optimize certain code patterns, resulting in the generation of malformed or incorrect machine code that can be exploited by remote attackers. The vulnerability is classified as an elevation of privilege issue, meaning that an attacker could potentially execute arbitrary code with the privileges of the targeted application or system. This represents a significant concern for enterprise environments where .NET applications are widely deployed, as it could allow attackers to gain unauthorized access to sensitive systems and data.
The technical nature of this vulnerability stems from improper handling of specific optimization algorithms within the RyuJIT compiler. When the compiler processes certain combinations of instructions, particularly those involving complex control flow and data manipulation, it fails to properly validate the optimization decisions it makes. This leads to the generation of machine code that contains unexpected behavior patterns, including potential buffer overflows, invalid memory accesses, or instruction sequence manipulations that could be exploited. The vulnerability is particularly dangerous because it operates at the compiler level, meaning that malicious code could be injected during the compilation process itself, making it difficult to detect through traditional runtime security measures. According to CWE classification, this vulnerability maps to CWE-129, which deals with improper validation of array indices, and CWE-682, which covers incorrect computation of buffer or array size. The flaw demonstrates characteristics consistent with the ATT&CK technique T1059.001, where adversaries use legitimate compiler tools to execute malicious code.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to escalate privileges within affected systems. Remote attackers could craft specially designed .NET applications that, when compiled and executed, would trigger the faulty optimization path in RyuJIT. This could lead to complete system compromise, especially when the vulnerable applications run with elevated privileges or access to sensitive resources. The vulnerability affects systems where the .NET Framework 4.6 is installed and where applications are compiled using the RyuJIT compiler, making it particularly concerning for web applications, server environments, and any system running .NET-based services. Organizations using .NET Framework 4.6 in production environments face significant risk, as this vulnerability could be exploited to bypass security controls and gain unauthorized access to critical infrastructure. The remote exploitation capability means that attackers do not need physical access to systems, making this vulnerability particularly dangerous in cloud and distributed computing environments where .NET applications are commonly deployed.
Mitigation strategies for this vulnerability require immediate action from system administrators and security teams. The primary recommendation is to install the official Microsoft security updates that address the RyuJIT compiler flaw, which were released as part of the regular security update cycle. Organizations should also consider implementing runtime monitoring to detect anomalous code execution patterns that might indicate exploitation attempts. Additional protective measures include restricting the execution of untrusted .NET applications, implementing application whitelisting policies, and ensuring that .NET Framework installations are kept current with the latest security patches. Security teams should also consider disabling unnecessary compiler features or using alternative compilation methods that do not utilize the vulnerable RyuJIT optimization paths. The vulnerability highlights the importance of comprehensive security testing for compiler components and the need for robust validation of optimization algorithms. Organizations should also review their incident response procedures to ensure they can quickly detect and respond to exploitation attempts targeting this specific vulnerability, given its potential for remote code execution and privilege escalation.