CVE-2009-2515 in Windows
Summary
by MITRE
Integer underflow in the kernel in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 Gold and SP2 allows local users to gain privileges via a crafted application that triggers an incorrect truncation of a 64-bit integer to a 32-bit integer, aka "Windows Kernel Integer Underflow Vulnerability."
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Analysis
by VulDB Data Team • 08/23/2021
The vulnerability identified as CVE-2009-2515 represents a critical integer underflow condition within the Windows kernel operating systems, affecting a wide range of Microsoft products including Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, as well as Server 2008 Gold and SP2. This flaw stems from improper handling of 64-bit integer values that are incorrectly truncated to 32-bit representations during kernel operations, creating a pathway for privilege escalation attacks. The vulnerability manifests when a malicious application triggers specific kernel functions that process large integer values, causing the system to perform arithmetic operations on values that exceed the maximum representable value for 32-bit integers, resulting in unexpected negative values.
The technical implementation of this vulnerability involves kernel-level memory management routines that fail to properly validate integer boundaries when processing 64-bit values that are subsequently cast or truncated to 32-bit data types. This integer underflow condition occurs within the kernel's memory allocation and management functions, where the system calculates buffer sizes or memory offsets based on improperly validated integer inputs. When a 64-bit value that exceeds the maximum positive value of a 32-bit integer is processed, the truncation operation causes the value to wrap around to a negative number, which can then be used to manipulate kernel memory structures. The flaw is particularly dangerous because it operates at the kernel level, where any successful exploitation can result in complete system compromise and privilege escalation to kernel-level access.
From an operational perspective, this vulnerability presents a significant risk to enterprise environments as local users can leverage the integer underflow to execute arbitrary code with kernel privileges, effectively bypassing standard user access controls and system security mechanisms. The attack requires only local system access, making it particularly concerning as it can be exploited by malware or malicious users who have already gained user-level access to a target system. The privilege escalation occurs because the underflowed integer values can be used to manipulate kernel data structures, potentially allowing attackers to modify system memory, bypass security checks, or execute code with the highest system privileges. This vulnerability aligns with CWE-191, which specifically addresses integer underflow conditions, and represents a classic example of how improper integer handling can create security weaknesses in operating system kernels.
The impact of this vulnerability extends beyond individual system compromise to potentially affect entire network infrastructures, as compromised systems can serve as launching points for further attacks. Attackers can exploit this condition to gain unauthorized access to sensitive system resources, modify critical system files, or establish persistent backdoors within the compromised environment. The vulnerability's presence in multiple Windows versions indicates a fundamental design flaw in the kernel's integer handling mechanisms that was not adequately addressed through standard security updates. Organizations should implement immediate mitigations including applying Microsoft security patches, disabling unnecessary services, and implementing network segmentation to limit potential attack vectors. The vulnerability also demonstrates the importance of proper integer overflow and underflow validation in kernel code, as specified in security standards such as the CERT Secure Coding Standards and the OWASP Top Ten, which emphasize the need for comprehensive input validation and proper integer type management in security-critical applications.