CVE-2006-0634 in Borland
Summary
by MITRE
Borland C++Builder 6 (BCB6) with Update Pack 4 Enterprise edition (ent_upd4) evaluates the "i>sizeof(int)" expression to false when i equals -1, which might introduce integer overflow vulnerabilities into applications that could be exploited by context-dependent attackers.
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Analysis
by VulDB Data Team • 07/19/2018
The vulnerability described in CVE-2006-0634 represents a critical integer overflow issue within Borland C++Builder 6 Enterprise edition with Update Pack 4. This flaw manifests in the compiler's handling of expression evaluation where the condition "i>sizeof(int)" returns false when the integer variable i is assigned the value -1. The root cause stems from how the compiler processes signed integer comparisons against unsigned size values, creating a scenario where legitimate code paths may be bypassed due to incorrect boolean evaluation. This behavior fundamentally violates expected arithmetic operations and can lead to severe security implications for applications compiled with this version of the development environment.
The technical implementation of this vulnerability occurs at the compiler level where the evaluation of the expression "i>sizeof(int)" fails to properly account for the signed nature of the variable i when compared against the unsigned result of sizeof(int). When i equals -1, the compiler incorrectly evaluates this expression as false, which can result in code sections being skipped or executed under unintended conditions. This misevaluation creates opportunities for integer overflow conditions to persist in compiled applications, particularly affecting code that relies on proper bounds checking and conditional logic. The flaw specifically impacts applications where signed integer variables are compared against size_t or unsigned integer types, creating a pathway for attackers to manipulate program flow through carefully crafted inputs.
The operational impact of this vulnerability extends beyond simple compilation errors to potentially enable serious exploitation scenarios. Applications compiled with BCB6 ent_upd4 may exhibit unexpected behavior when processing inputs that trigger the specific integer overflow condition, creating opportunities for attackers to manipulate program execution flow. The vulnerability is context-dependent, meaning that exploitation requires specific conditions to be met, typically involving inputs that cause i to assume the value -1 while also triggering the problematic comparison. This characteristic makes the vulnerability particularly dangerous as it can be leveraged in scenarios where attackers can influence program variables through input manipulation, potentially leading to buffer overflows, arbitrary code execution, or denial of service conditions.
Security implications of this vulnerability align with CWE-191, which describes integer underflow or overflow conditions, and can be mapped to ATT&CK technique T1059 for execution through code injection. The vulnerability creates a pathway for attackers to manipulate integer values in ways that bypass normal program validation, potentially allowing them to exploit other weaknesses in the application's input handling or memory management. Organizations using this compiler version face significant risk as any application compiled with the affected toolchain could contain exploitable integer overflow conditions. The vulnerability particularly affects applications that perform extensive input validation, memory management, or mathematical operations where integer overflow could lead to privilege escalation or system compromise.
Mitigation strategies for this vulnerability require immediate action to address the root cause at the compilation level. The primary recommendation involves upgrading to a newer version of the Borland C++Builder development environment that does not exhibit this problematic behavior in expression evaluation. Organizations should conduct comprehensive code reviews of applications compiled with BCB6 ent_upd4 to identify potential integer overflow conditions that may have been introduced through this compiler flaw. Additionally, implementing runtime protections such as stack canaries, address space layout randomization, and input validation mechanisms can help reduce the exploitability of any remaining vulnerable code. Security teams should also consider implementing static analysis tools that can detect potential integer overflow conditions in code, particularly focusing on comparisons between signed and unsigned integers. The vulnerability demonstrates the critical importance of compiler quality and the need for thorough testing of development environments to prevent the introduction of security flaws into applications at the source code level.