CVE-2019-19787 in ATasm
Summary
by MITRE
ATasm 1.06 has a stack-based buffer overflow in the get_signed_expression() function in setparse.c via a crafted .m65 file.
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Analysis
by VulDB Data Team • 03/12/2024
The vulnerability identified as CVE-2019-19787 represents a critical stack-based buffer overflow flaw within the ATasm 1.06 assembler utility. This issue manifests specifically within the get_signed_expression() function located in the setparse.c source file, creating a significant security risk when processing maliciously crafted input files. The vulnerability occurs during the parsing of .m65 files, which are assembly source files used in the context of 6502 processor architecture development, making this a targeted attack vector for developers and embedded systems engineers working with legacy hardware platforms.
The technical exploitation of this buffer overflow stems from inadequate input validation and bounds checking within the get_signed_expression() function. When ATasm encounters a specially crafted .m65 file containing malicious data sequences, the parser fails to properly constrain buffer allocations, allowing attacker-controlled data to overwrite adjacent memory locations on the stack. This memory corruption can lead to arbitrary code execution, system instability, or privilege escalation depending on the execution context. The vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in the Common Weakness Enumeration catalog and represents one of the most prevalent and dangerous types of buffer overflow vulnerabilities.
The operational impact of CVE-2019-19787 extends beyond simple denial of service scenarios to encompass potential system compromise and data integrity violations. Attackers could leverage this vulnerability to execute malicious code on systems running ATasm 1.06, particularly in development environments where assembly code analysis and compilation are routine activities. Given that this vulnerability affects an assembler tool used in embedded systems development, the potential for exploitation in production environments where such tools are integrated into build processes is significant. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to gain unauthorized code execution through malformed input processing.
Mitigation strategies for this vulnerability should prioritize immediate patching of ATasm to version 1.07 or later, which contains the necessary fixes for the buffer overflow condition. System administrators and developers should implement input validation measures to prevent processing of untrusted .m65 files, particularly in automated build environments. Additional protective measures include implementing sandboxing techniques for assembly file processing, deploying runtime application self-protection mechanisms, and conducting regular security assessments of development toolchains. Organizations should also consider network segmentation and access controls to limit exposure of systems running vulnerable versions of ATasm, while maintaining comprehensive monitoring for suspicious file processing activities that could indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices in development tools and highlights the need for regular security updates in specialized software used across multiple domains including embedded systems, firmware development, and legacy platform maintenance.