CVE-2015-2481 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-2015-2479 and CVE-2015-2480.
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Analysis
by VulDB Data Team • 06/09/2022
The RyuJIT optimization vulnerability represents a critical flaw in Microsoft's .NET Framework 4.6 compiler that fundamentally undermines code execution integrity. This vulnerability resides within the RyuJIT compiler's optimization routines where it fails to properly handle certain edge cases during code generation, creating opportunities for malicious code injection. The flaw manifests specifically during optimization passes when the compiler incorrectly processes specific instruction sequences, leading to unpredictable code behavior that can be exploited by remote attackers. The vulnerability is particularly concerning because it operates at the compiler level, meaning that legitimate applications compiled with affected .NET Framework versions may inadvertently contain exploitable code patterns that attackers can leverage.
The technical root cause of this vulnerability lies in improper handling of optimization algorithms within the RyuJIT compiler's backend processing. When the compiler attempts to optimize certain complex control flow patterns or specific mathematical operations, it generates incorrect intermediate representation code that, when executed, can bypass normal security boundaries. This flaw falls under CWE-697, which specifically addresses incorrect comparison issues, as the compiler's optimization logic fails to properly validate or handle certain edge cases in its optimization decisions. The vulnerability enables attackers to manipulate the compiled output through carefully crafted input that triggers the faulty optimization path, resulting in code execution that was not intended by the original application developer.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it affects the fundamental security model of .NET applications running on affected systems. Remote attackers can leverage this vulnerability to execute arbitrary code with the privileges of the compromised application, potentially leading to complete system compromise if the application runs with elevated permissions. The vulnerability is particularly dangerous because it can be triggered through legitimate .NET application execution without requiring special privileges or direct system access. Attackers can craft malicious .NET applications that, when compiled and executed, exploit the optimization flaw to gain unauthorized code execution capabilities. This vulnerability affects all applications compiled with .NET Framework 4.6 and running on Windows systems, creating a broad attack surface that spans enterprise applications, web services, and client applications.
Mitigation strategies for this vulnerability require immediate patching of affected .NET Framework installations, as Microsoft released security updates specifically addressing the RyuJIT optimization flaw. Organizations should prioritize deployment of the latest .NET Framework updates and consider implementing application whitelisting policies to prevent execution of untrusted .NET applications. The vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as attackers can leverage the compromised compiler to execute arbitrary code through legitimate application paths. Additional defensive measures include monitoring for unusual code execution patterns, implementing runtime application self-protection mechanisms, and conducting thorough security assessments of all .NET applications to identify potential exploitation vectors. System administrators should also consider disabling unnecessary .NET Framework features and implementing strict access controls to limit the potential impact of successful exploitation attempts.