CVE-2019-19785 in ATasm
Summary
by MITRE
ATasm 1.06 has a stack-based buffer overflow in the to_comma() function in asm.c via a crafted .m65 file.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 03/12/2024
The vulnerability identified as CVE-2019-19785 represents a critical stack-based buffer overflow flaw within the ATasm 1.06 assembler software. This issue manifests specifically within the to_comma() function located in the asm.c source file, creating a significant security risk when processing malformed input files. The vulnerability arises from insufficient input validation and bounds checking during the parsing of .m65 assembly files, which are commonly used in 6502 processor assembly language development. The buffer overflow occurs when the assembler encounters specially crafted input that exceeds the allocated stack buffer space, potentially leading to arbitrary code execution or system instability.
The technical nature of this vulnerability places it squarely within CWE-121 Stack-based Buffer Overflow, a well-documented weakness category that encompasses buffer overflows occurring on the stack memory region. The attack vector specifically targets the parsing logic of the assembler, where the to_comma() function fails to properly validate the length of input data before copying it into a fixed-size stack buffer. This flaw enables an attacker to manipulate the program's execution flow by overwriting adjacent stack memory, potentially allowing for privilege escalation or complete system compromise. The vulnerability demonstrates a classic lack of input sanitization that violates fundamental secure coding practices and represents a critical failure in memory management within the assembler's codebase.
The operational impact of CVE-2019-19785 extends beyond simple denial of service scenarios, as it creates potential for remote code execution in environments where the vulnerable assembler processes untrusted input files. Attackers could craft malicious .m65 files that, when processed by ATasm 1.06, would trigger the buffer overflow condition and potentially execute arbitrary code with the privileges of the user running the assembler. This vulnerability affects developers and system administrators who rely on ATasm for embedded systems development, particularly in environments where assembly code generation and processing occur in untrusted contexts. The risk is amplified in continuous integration environments where automated build processes might inadvertently process compromised assembly files, creating a potential attack surface for lateral movement within development infrastructures.
Mitigation strategies for this vulnerability should prioritize immediate patching of the ATasm 1.06 software to address the buffer overflow condition in the to_comma() function. Organizations should implement strict input validation measures and sanitize all assembly source files before processing, particularly in automated environments where multiple users contribute to code repositories. The remediation approach should include bounds checking modifications to ensure that input data lengths are properly verified before buffer operations occur, aligning with secure coding guidelines from the CERT Secure Coding Standards. Additionally, deployment of runtime protections such as stack canaries and address space layout randomization can provide defense-in-depth measures against exploitation attempts. Security monitoring should include detection of unusual file processing patterns and implementation of sandboxed execution environments for assembly file analysis to prevent potential exploitation of this vulnerability in production systems.