CVE-2017-17814 in NASM
Summary
by MITRE
In Netwide Assembler (NASM) 2.14rc0, there is a use-after-free in do_directive in asm/preproc.c that will cause a remote denial of service attack.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-17814 represents a critical use-after-free condition within the Netwide Assembler (NASM) version 2.14rc0, specifically within the do_directive function located in the asm/preproc.c source file. This flaw occurs during the preprocessing phase of assembly code compilation, where the assembler processes directives that control the assembly process and manage conditional compilation. The nature of this vulnerability stems from improper memory management practices where dynamically allocated memory is accessed after it has been freed, creating a scenario that can be exploited by malicious actors to disrupt normal operation of the assembler.
The technical implementation of this vulnerability involves the manipulation of assembly directives that trigger the problematic code path in the preprocessor component of NASM. When an attacker crafts malicious assembly input containing specially formatted directives, the do_directive function processes these inputs without proper validation of memory references, leading to the execution of code that attempts to access memory that has already been deallocated. This memory access violation typically results in a segmentation fault or similar memory management exception that terminates the assembler process, effectively creating a remote denial of service condition.
From an operational perspective, this vulnerability poses significant risks to systems that rely on NASM for compiling assembly code, particularly in automated build environments, compiler toolchains, or systems that process untrusted assembly input from external sources. The remote denial of service aspect means that an attacker located outside the target system can potentially disrupt legitimate assembly compilation processes by submitting malicious input files, making this particularly dangerous in networked environments where assembly code might be processed automatically. The impact extends beyond simple service disruption as it can prevent legitimate software development activities and compromise automated build pipelines that depend on NASM functionality.
The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, and demonstrates how improper memory management can create security risks in development tools. From an ATT&CK framework perspective, this vulnerability could be categorized under T1499.004 for network denial of service attacks, as it enables remote exploitation to disrupt system services. Additionally, it reflects weaknesses in software development practices related to memory safety and input validation that are commonly addressed through secure coding practices and static analysis tools. Organizations should consider this vulnerability as part of their broader software supply chain security posture, particularly when using NASM in automated environments or when processing untrusted assembly code inputs. The recommended mitigations include immediate patching to the latest stable version of NASM, implementing input validation for assembly code processing, and monitoring for potential exploitation attempts in system logs and network traffic.
The broader implications of this vulnerability extend to software development ecosystems where assembly code compilation is a common requirement, including embedded systems development, system programming, and low-level software engineering tasks. The use-after-free condition represents a fundamental memory management error that can potentially be escalated to more severe exploits if additional vulnerabilities exist within the same codebase or related components, making comprehensive security assessments of development toolchains essential for maintaining overall system security.