CVE-2017-17811 in NASM
Summary
by MITRE
In Netwide Assembler (NASM) 2.14rc0, there is a heap-based buffer overflow that will cause a remote denial of service attack, related to a strcpy in paste_tokens in asm/preproc.c, a similar issue to CVE-2017-11111.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-17811 affects the Netwide Assembler (NASM) version 2.14rc0, representing a critical heap-based buffer overflow condition that fundamentally compromises the stability and security of the assembly language compiler. This issue resides within the preprocessor component of NASM, specifically within the paste_tokens function located in the asm/preproc.c source file. The vulnerability manifests through the improper handling of string operations, particularly the use of strcpy() which lacks bounds checking mechanisms. When processing certain input patterns, the vulnerable code fails to validate the length of source data against the destination buffer capacity, creating an exploitable condition that allows attackers to overwrite adjacent heap memory regions.
The technical flaw stems from the insecure use of the strcpy() function which copies data from an untrusted source without verifying that the destination buffer has sufficient capacity to accommodate the incoming data. This particular implementation in the paste_tokens function demonstrates a classic buffer overflow vulnerability that aligns with CWE-121, which categorizes heap-based buffer overflows resulting from inadequate bounds checking during string operations. The vulnerability operates at the preprocessor level where NASM processes assembly source files before compilation, making it particularly dangerous as it can be triggered during the parsing phase of any assembly code that contains maliciously crafted input sequences. The remote denial of service attack vector implies that an attacker could potentially craft malicious assembly code or input files that when processed by the vulnerable NASM version would cause the application to crash or become unresponsive.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a fundamental security weakness that could potentially be exploited to achieve more severe consequences. While the immediate effect is a remote denial of service attack, the heap corruption nature of the vulnerability creates opportunities for more sophisticated exploitation techniques. The vulnerability's similarity to CVE-2017-11111 indicates a pattern of insecure string handling within NASM's preprocessor subsystem, suggesting that multiple related functions may share the same vulnerability pattern. This creates a broader security surface that security professionals must consider when assessing the overall risk of using NASM in production environments, particularly in scenarios where assembly code is processed from untrusted sources or when NASM is used as part of automated build systems or continuous integration pipelines.
Mitigation strategies for CVE-2017-17811 should focus on immediate patching of affected NASM versions to the latest stable releases that contain fixed implementations of the vulnerable string handling functions. Organizations should implement input validation measures to sanitize assembly code sources and avoid processing untrusted assembly files through NASM. The use of address sanitization tools and memory protection mechanisms such as stack canaries, address space layout randomization, and heap protection features can provide additional defense-in-depth measures. Security monitoring should include detection of abnormal NASM process behavior and memory allocation patterns that might indicate exploitation attempts. From an operational standpoint, maintaining updated versions of development tools and implementing proper code review processes for assembly code can significantly reduce the risk exposure. The vulnerability also highlights the importance of adhering to secure coding practices, particularly around string manipulation functions, as outlined in the ATT&CK framework's software development practices that emphasize preventing buffer overflow conditions through proper bounds checking and secure coding standards.