CVE-2006-1511 in .NET Framework
Summary
by MITRE
Buffer overflow in the ILASM assembler in the Microsoft .NET 1.0 and 1.1 Framework might allow user-assisted attackers to execute arbitrary code via a .il file that calls a function with a long name.
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Analysis
by VulDB Data Team • 04/05/2017
The vulnerability identified as CVE-2006-1511 represents a critical buffer overflow condition within the ILASM assembler component of Microsoft .NET Framework versions 1.0 and 1.1. This flaw exists in the intermediate language assembler responsible for converting il source files into executable assemblies. The vulnerability specifically manifests when processing .il files containing function calls with excessively long names, creating a scenario where memory boundaries are exceeded during the parsing process. The buffer overflow occurs due to insufficient input validation and boundary checking within the assembler's name handling routines, allowing attackers to manipulate the assembly process through crafted malicious input files.
The technical exploitation of this vulnerability leverages the fundamental principle of buffer overflow attacks where attacker-controlled data exceeds the allocated memory space for storing function names. When the ILASM tool processes an .il file containing a function with an unusually long name, the tool's internal buffers fail to properly validate the length of the identifier, leading to memory corruption. This memory corruption can overwrite adjacent memory locations including return addresses, function pointers, or other critical control data structures. The vulnerability falls under CWE-121, which categorizes buffer overflow conditions where insufficient bounds checking allows memory to be overwritten, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers could potentially execute arbitrary code through controlled assembly generation.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to gain unauthorized access to systems running vulnerable .NET Framework versions. The user-assisted nature of the attack means that the victim must intentionally process a malicious .il file, typically through a trusted assembly process or development environment. This creates a significant risk in development environments where developers might unknowingly compile malicious code or in scenarios where automated build processes handle untrusted input. The attack vector is particularly concerning in enterprise environments where .NET applications are commonly deployed, as the vulnerability affects the core assembly tooling rather than just runtime execution. The potential for privilege escalation exists when attackers can manipulate the assembly process to inject malicious code into legitimate applications, making this vulnerability particularly dangerous in multi-user or shared hosting environments.
Mitigation strategies for CVE-2006-1511 focus on both immediate patching and operational security measures. Microsoft released security updates for the .NET Framework versions 1.0 and 1.1 that addressed the buffer overflow condition by implementing proper input validation and boundary checking. Organizations should prioritize applying these security patches immediately to eliminate the vulnerability. Additionally, implementing input validation controls at the file processing level can provide defense in depth, ensuring that .il files are validated for acceptable name lengths before processing. Network segmentation and access controls should limit which users can execute assembly tools, reducing the attack surface. Security monitoring should include detection of unusual assembly process activities, particularly when processing files from untrusted sources. The vulnerability also highlights the importance of secure coding practices and input sanitization, as outlined in OWASP top ten security risks and Microsoft security development lifecycle guidelines. Regular security assessments and penetration testing of .NET environments should include verification of proper buffer handling in assembly tools to prevent similar vulnerabilities from being introduced in future versions.