CVE-2017-14228 in Netwide Assembler
Summary
by MITRE
In Netwide Assembler (NASM) 2.14rc0, there is an illegal address access in the function paste_tokens() in preproc.c, aka a NULL pointer dereference. It will lead to remote denial of service.
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Analysis
by VulDB Data Team • 12/28/2022
The vulnerability identified as CVE-2017-14228 represents a critical NULL pointer dereference flaw within the Netwide Assembler (NASM) version 2.14rc0. This issue manifests in the paste_tokens() function located within the preproc.c source file, where the software fails to properly validate pointer references during the preprocessing phase of assembly code compilation. The vulnerability arises when the assembler encounters specific input patterns that cause the function to attempt accessing a null memory address, resulting in an abrupt program termination. This flaw affects the core preprocessing functionality that handles token concatenation operations, making it particularly dangerous as it can be triggered during normal assembly processing of source files.
The technical implementation of this vulnerability stems from inadequate input validation within the preprocessor's token handling mechanism. When NASM processes assembly source code containing malformed or specially crafted directives, the paste_tokens() function receives a null pointer reference that it attempts to dereference without proper null checking. This condition violates fundamental memory safety principles and aligns with CWE-476, which categorizes NULL pointer dereference as a common programming error that can lead to application crashes or system instability. The vulnerability's exploitation requires an attacker to provide carefully constructed input that triggers the specific code path within the preprocessor, making it a remote denial of service vector that can be leveraged by malicious actors.
The operational impact of CVE-2017-14228 extends beyond simple program termination, as it represents a significant threat to systems relying on NASM for assembly code compilation. This vulnerability can be exploited in environments where NASM is used to process untrusted input, such as automated build systems, code analysis tools, or web applications that compile user-supplied assembly code. The remote denial of service aspect means that attackers can potentially disrupt legitimate compilation processes across multiple systems, affecting development workflows and potentially causing cascading failures in automated testing and deployment pipelines. Security researchers have classified this vulnerability under ATT&CK technique T1499.004, which covers network denial of service attacks, as the vulnerability can be leveraged to disrupt normal system operations through controlled input manipulation.
Mitigation strategies for CVE-2017-14228 should focus on immediate patching of affected NASM installations to version 2.14 or later, where the NULL pointer dereference has been resolved through proper input validation. System administrators should implement strict input sanitization measures when processing assembly code, particularly in environments where untrusted input is accepted. Additional protective measures include deploying network segmentation to limit access to systems running NASM, implementing monitoring for unusual compilation activities, and ensuring that automated build processes are isolated from potentially malicious inputs. The vulnerability highlights the importance of robust error handling in compiler and assembler tools, as these components often serve as foundational elements in software development environments where memory safety violations can have widespread consequences. Organizations should also consider implementing static analysis tools to identify similar patterns in other software components and establish comprehensive testing procedures that include fuzzing to detect potential NULL pointer dereference conditions in their toolchains.