CVE-2008-2719 in Netwide Assembler
Summary
by MITRE
Off-by-one error in the ppscan function (preproc.c) in Netwide Assembler (NASM) 2.02 allows context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted file that triggers a stack-based buffer overflow.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2008-2719 represents a critical security flaw in the Netwide Assembler version 2.02, specifically within the ppscan function located in the preproc.c source file. This issue manifests as an off-by-one error that creates a condition where the assembler fails to properly validate input boundaries during preprocessing operations. The flaw occurs when processing malformed assembly files that contain crafted sequences designed to exploit the boundary condition, ultimately leading to unpredictable program behavior.
The technical implementation of this vulnerability stems from improper bounds checking in the ppscan function which handles preprocessing operations for assembly source code. When NASM encounters a specially crafted input file, the off-by-one error causes the function to write one byte beyond the allocated buffer space, creating a stack-based buffer overflow condition. This type of vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, where insufficient boundary checks allow memory corruption. The vulnerability is context-dependent meaning that successful exploitation requires specific conditions related to the input file structure and the manner in which NASM processes the preprocessor directives.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable arbitrary code execution, making it particularly dangerous for environments where NASM is used to process untrusted assembly code. An attacker could craft malicious assembly files that, when processed by the vulnerable NASM version, would cause the assembler to crash or potentially execute malicious code with the privileges of the user running NASM. This creates significant risks in automated build systems, code analysis tools, or any environment where NASM processes external assembly inputs. The vulnerability aligns with ATT&CK technique T1059.006 for execution through interpreted languages and T1499.004 for denial of service through resource exhaustion, particularly when considering the potential for repeated exploitation.
Mitigation strategies for CVE-2008-2719 require immediate action to upgrade to a patched version of NASM where the off-by-one error in the ppscan function has been corrected. System administrators should ensure that all instances of NASM are updated to version 2.03 or later, which contains the necessary boundary checks to prevent the buffer overflow condition. Additionally, organizations should implement input validation procedures for any assembly files processed through NASM, particularly those received from untrusted sources. Security monitoring should include detection of unusual NASM crash patterns or execution behavior, and network segmentation should be considered to limit potential exploitation in automated environments where NASM might be exposed to untrusted inputs. The fix implemented in subsequent versions demonstrates proper defensive programming practices that align with secure coding guidelines and address the fundamental CWE-121 vulnerability through robust boundary validation mechanisms.