CVE-2018-10016 in Netwide Assembler
Summary
by MITRE
Netwide Assembler (NASM) 2.14rc0 has a division-by-zero vulnerability in the expr5 function in asm/eval.c via a malformed input file.
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Analysis
by VulDB Data Team • 01/24/2020
The vulnerability identified as CVE-2018-10016 represents a critical division-by-zero flaw within the Netwide Assembler (NASM) version 2.14rc0, specifically within the expr5 function located in the asm/eval.c source file. This issue arises when NASM processes malformed input files that contain expressions leading to a division operation with a zero denominator during the assembly evaluation phase. The vulnerability demonstrates a classic software error pattern where input validation fails to properly handle edge cases, creating an opportunity for abnormal program termination or potential code execution manipulation.
The technical implementation of this vulnerability occurs during the expression evaluation phase of NASM's compilation process, where the expr5 function processes mathematical expressions and arithmetic operations. When a malformed input file contains an expression that results in a division by zero operation, the function fails to properly validate the denominator value before performing the division, leading to a runtime exception. This flaw falls under the CWE-369 vulnerability category, which specifically addresses the division by zero condition that can cause program crashes or unexpected behavior. The vulnerability is particularly concerning as it exists in a code processing tool that is widely used in software development environments, creating potential for both denial of service and exploitation scenarios.
The operational impact of this vulnerability extends beyond simple program termination, as it can be leveraged to cause denial of service attacks against systems that rely on NASM for assembly processing. An attacker could craft malicious input files that trigger the division-by-zero condition, causing NASM to crash or behave unpredictably during the assembly process. This could be particularly damaging in automated build environments or continuous integration systems where NASM is used to process source code files. The vulnerability also aligns with ATT&CK technique T1059.001, which covers the use of command-line interfaces, as NASM is often invoked through command-line operations within development workflows, making it a potential vector for system compromise.
Mitigation strategies for this vulnerability should include immediate patching of NASM to version 2.14 or later, which contains the necessary fixes to properly validate division operations within expression evaluation. Organizations should also implement input validation measures when processing assembly files from untrusted sources, including sanitizing input parameters and monitoring for malformed expressions. Additionally, system administrators should consider implementing sandboxing or containment strategies when executing NASM on potentially malicious input files. The vulnerability highlights the importance of proper error handling and input validation in development tools, particularly those that process user-supplied code, as such tools often become targets for exploitation due to their privileged execution contexts within development environments.