CVE-2008-1685 in gcc
Summary
by MITRE
** DISPUTED ** gcc 4.2.0 through 4.3.0 in GNU Compiler Collection, when casts are not used, considers the sum of a pointer and an int to be greater than or equal to the pointer, which might lead to removal of length testing code that was intended as a protection mechanism against integer overflow and buffer overflow attacks, and provide no diagnostic message about this removal. NOTE: the vendor has determined that this compiler behavior is correct according to section 6.5.6 of the C99 standard (aka ISO/IEC 9899:1999).
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability described in CVE-2008-1685 relates to a specific behavior in the GNU Compiler Collection versions 4.2.0 through 4.3.0 that affects how pointer arithmetic is handled during compilation. This issue occurs when code does not explicitly use casts in pointer arithmetic operations, leading to compiler optimizations that may inadvertently remove critical security checks designed to prevent buffer overflow attacks. The fundamental problem arises from the compiler's interpretation of pointer arithmetic semantics, which according to the vendor, aligns with the C99 standard's section 6.5.6 specification. This standard defines the behavior of pointer arithmetic operations, including how pointer and integer addition should be evaluated in the context of the language's memory model.
The technical flaw manifests when the compiler determines that the result of pointer arithmetic involving addition of a pointer and integer value is always greater than or equal to the original pointer address. This optimization assumes that pointer arithmetic will not produce results that could cause memory access violations or security exploits, but this assumption can be exploited by attackers to bypass security mechanisms. The vulnerability specifically targets the removal of length validation code that was explicitly written by developers to protect against integer overflow conditions and buffer overflows. When the compiler eliminates these checks based on its interpretation of pointer arithmetic rules, it creates a security gap where malicious input could cause memory corruption without proper bounds checking.
The operational impact of this vulnerability is significant for software systems compiled with affected GCC versions, as it effectively neutralizes security measures that developers implement to prevent memory corruption attacks. The vulnerability's exploitation potential is particularly concerning because it operates silently without generating any diagnostic messages or warnings during compilation, making it difficult for developers to identify when their security code has been inadvertently removed. This behavior can lead to applications that appear to function normally but contain critical security flaws that make them susceptible to buffer overflow attacks, integer overflow exploits, and other memory corruption vulnerabilities. The issue affects the broader software supply chain since any application compiled with these GCC versions could potentially be vulnerable, regardless of the application's specific security implementation.
The security implications extend beyond simple code removal, as this behavior can be leveraged by attackers to bypass security controls that are fundamental to preventing memory corruption exploits. From a cybersecurity perspective, this vulnerability demonstrates how compiler behavior can inadvertently create security weaknesses that are not immediately apparent to developers. The vulnerability's classification aligns with CWE-129, which addresses improper validation of array indices, and relates to ATT&CK technique T1055.011 for process injection and T1068 for privilege escalation through memory corruption. Organizations using affected GCC versions should consider implementing additional runtime protections, such as stack canaries, address space layout randomization, and memory protection mechanisms, to mitigate the risk of exploitation. The vendor's determination that this behavior is correct according to the C99 standard highlights the complexity of balancing language specification compliance with security requirements in compiler design.