CVE-2017-17810 in NASM
Summary
by MITRE
In Netwide Assembler (NASM) 2.14rc0, there is a "SEGV on unknown address" that will cause a remote denial of service attack, because asm/preproc.c mishandles macro calls that have the wrong number of arguments.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-17810 affects the Netwide Assembler (NASM) version 2.14rc0, representing a critical remote denial of service condition that manifests as a segmentation fault during macro processing. This flaw exists within the preprocessor component of NASM, specifically in the asm/preproc.c file where the system fails to properly validate macro argument counts during macro invocation. The issue arises when malformed macro calls containing an incorrect number of arguments are processed, leading to unpredictable memory access patterns that ultimately result in program termination.
The technical implementation of this vulnerability stems from inadequate input validation within NASM's macro expansion mechanism. When the preprocessor encounters a macro definition and subsequent call, it fails to perform proper argument count verification before proceeding with expansion operations. This deficiency creates a scenario where the assembler attempts to access memory locations that are either unmapped or unauthorized, triggering a segmentation violation that crashes the entire assembly process. The vulnerability demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read conditions, and CWE-248, which addresses uncaught exceptions in programming languages. The flaw essentially creates a path where user-controlled input can manipulate the preprocessor's memory management routines, leading to arbitrary code execution termination.
From an operational perspective, this vulnerability presents significant risk to systems that rely on NASM for code compilation, particularly in automated build environments or web-based assembly services. Attackers can craft malicious assembly files containing malformed macro calls that, when processed by the vulnerable NASM version, will cause the assembler to crash and become unavailable for legitimate use. This denial of service condition affects not only individual development workflows but also continuous integration pipelines and automated testing environments that depend on reliable assembler functionality. The remote nature of this vulnerability means that an attacker could potentially exploit it through any mechanism that allows file upload or processing of user-supplied assembly code, making it particularly dangerous in web applications or services that accept assembly source files for compilation.
The impact of this vulnerability extends beyond simple service disruption, as it represents a fundamental flaw in the error handling mechanisms of the preprocessor component. The segmentation fault occurs during the macro expansion phase, which is a critical part of the assembly process where complex code transformations take place. This makes the vulnerability particularly dangerous in environments where multiple macro definitions and expansions occur simultaneously, as the crash could be triggered by relatively simple malformed input that would not be immediately apparent to users. Security practitioners should note that this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how seemingly benign preprocessing operations can become attack vectors when proper input validation is absent. Organizations using NASM in production environments should prioritize immediate patching or mitigation strategies, as the vulnerability provides no direct path for privilege escalation or data exfiltration but creates a substantial availability risk that can disrupt legitimate development and deployment processes.