CVE-2012-2519 in .NET Framework
Summary
by MITRE
Untrusted search path vulnerability in Entity Framework in ADO.NET in Microsoft .NET Framework 1.0 SP3, 1.1 SP1, 2.0 SP2, 3.5, 3.5.1, and 4 allows local users to gain privileges via a Trojan horse DLL in the current working directory, as demonstrated by a directory that contains a .NET application, aka ".NET Framework Insecure Library Loading Vulnerability."
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Analysis
by VulDB Data Team • 08/04/2021
The CVE-2012-2519 vulnerability represents a critical untrusted search path issue within Microsoft's Entity Framework implementation in ADO.NET across multiple .NET Framework versions including 1.0 SP3, 1.1 SP1, 2.0 SP2, 3.5, 3.5.1, and 4. This flaw enables local attackers to escalate privileges through malicious DLL injection techniques by placing Trojan horse DLLs in the current working directory of .NET applications. The vulnerability stems from the insecure loading behavior where the system searches for required assemblies in predictable locations including the current working directory before checking more secure system paths. This insecure library loading pattern directly aligns with CWE-427 and CWE-428, which classify the issue as an uncontrolled search path that allows attackers to influence the program's execution flow. The vulnerability is particularly dangerous because it operates at the foundational level of .NET Framework operations, affecting applications that utilize Entity Framework for database interactions and data access.
The technical exploitation of this vulnerability occurs when a .NET application running with elevated privileges loads assemblies from the current working directory without proper validation of the assembly's origin or integrity. Attackers can place a malicious DLL with the same name as a legitimate dependency in the application's directory, causing the system to load the attacker-controlled code instead of the legitimate library. This privilege escalation mechanism leverages the principle of least privilege violations where applications running with higher privileges inadvertently execute malicious code loaded from insecure paths. The attack vector specifically targets the dynamic loading mechanism used by .NET applications to resolve dependencies, creating a scenario where legitimate application functionality becomes compromised through malicious code injection. This vulnerability directly maps to ATT&CK technique T1059.001 for command and scripting interpreter and T1546.008 for exploit for privilege escalation through DLL side-loading.
The operational impact of CVE-2012-2519 extends beyond simple privilege escalation to encompass potential data compromise and system infiltration across environments utilizing affected .NET Framework versions. Organizations running applications that depend on Entity Framework become vulnerable to attackers who can manipulate the application's execution flow to execute arbitrary code with elevated privileges. The vulnerability affects both server-side and client-side applications that utilize ADO.NET data access components, creating widespread exposure across enterprise environments where .NET applications are prevalent. This includes web applications, desktop applications, and services that utilize Entity Framework for data operations, making the attack surface particularly broad. The vulnerability's persistence stems from the fundamental design flaw in how .NET Framework handles assembly resolution, which does not implement proper path validation or integrity checking mechanisms before loading assemblies from potentially compromised directories. Organizations with legacy applications running on affected .NET Framework versions face significant risk as these applications continue to operate with elevated privileges while being susceptible to this form of attack.
Mitigation strategies for CVE-2012-2519 focus on both immediate defensive measures and long-term architectural improvements to prevent insecure library loading. Microsoft recommended applying the appropriate security patches and updates to affected .NET Framework versions, which address the root cause by implementing proper assembly resolution validation. System administrators should implement directory permissions controls to restrict write access to application directories, particularly those containing .NET applications, to prevent unauthorized DLL placement. The implementation of application whitelisting policies using tools like AppLocker can prevent execution of unauthorized DLLs by enforcing strict binary approval processes. Additionally, developers should implement proper assembly loading techniques that explicitly specify assembly locations and validate assembly integrity before loading. Organizations should conduct comprehensive vulnerability assessments to identify applications running on affected .NET Framework versions and prioritize patching efforts accordingly. The vulnerability highlights the importance of secure coding practices and proper assembly resolution methodologies, emphasizing the need for defensive programming techniques that prevent insecure library loading behaviors. Regular security monitoring and intrusion detection systems should be configured to alert on suspicious DLL loading activities, particularly in directories containing .NET applications, to provide early warning of potential exploitation attempts.