CVE-2007-0229 in Mac OS X
Summary
by MITRE
Integer overflow in the ffs_mountfs function in Mac OS X 10.4.8 and FreeBSD 6.1 allows local users to cause a denial of service (panic) and possibly gain privileges via a crafted DMG image that causes "allocation of a negative size buffer" leading to a heap-based buffer overflow, a related issue to CVE-2006-5679. NOTE: a third party states that this issue does not cross privilege boundaries in FreeBSD because only root may mount a filesystem.
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Analysis
by VulDB Data Team • 03/08/2025
The vulnerability described in CVE-2007-0229 represents a critical integer overflow flaw affecting file system mounting operations in Mac OS X 10.4.8 and FreeBSD 6.1 systems. This issue manifests within the ffs_mountfs function where improper handling of file system size parameters leads to a scenario where a maliciously crafted DMG image can trigger a negative buffer allocation. The vulnerability operates at the kernel level and demonstrates how seemingly benign file system operations can be exploited to compromise system stability and potentially escalate privileges. The integer overflow occurs during the file system mounting process when the system attempts to allocate memory buffers based on corrupted size calculations derived from the crafted image metadata. This flaw specifically targets the Fast File System (FFS) implementation and represents a classic heap-based buffer overflow condition that can be triggered through file system mount operations.
The technical execution of this vulnerability relies on manipulating the size parameters within DMG image headers to force the system into allocating memory with negative values. When the ffs_mountfs function processes these malformed parameters, it fails to properly validate the input size calculations, resulting in an integer overflow that subsequently causes the system to attempt to allocate a buffer of negative size. This memory allocation failure leads to system panic conditions and can potentially allow privilege escalation depending on the operating system implementation. The vulnerability is classified under CWE-190 as an integer overflow condition and aligns with ATT&CK technique T1068 which covers privilege escalation through kernel exploits. The flaw essentially creates a condition where legitimate system operations become vectors for malicious code execution or system instability.
The operational impact of CVE-2007-0229 extends beyond simple denial of service scenarios, as it can potentially enable local privilege escalation attacks. When a local user successfully exploits this vulnerability through a crafted DMG image, they can cause the system to panic and potentially gain elevated privileges to execute code with root-level permissions. The attack vector requires local access to the system since mounting operations typically require user interaction or system-level privileges, but the vulnerability's nature allows for escalation once successfully triggered. This makes the flaw particularly dangerous in environments where local users have access to potentially untrusted file system images or where automated mounting processes might be exploited. The vulnerability's relationship to CVE-2006-5679 indicates a broader pattern of integer overflow issues affecting file system implementations in Unix-like systems, highlighting the need for comprehensive input validation in kernel-level code.
Mitigation strategies for CVE-2007-0229 should focus on immediate system updates and patch management to address the underlying integer overflow in the ffs_mountfs function. System administrators must ensure that all Mac OS X and FreeBSD systems are updated to versions containing fixes for this vulnerability, as the issue affects core file system mounting operations that are fundamental to system operation. Additional protective measures include implementing strict file system mount policies, disabling automatic mounting of external media, and monitoring for suspicious file system activity. The vulnerability's classification under CWE-190 emphasizes the importance of robust integer overflow prevention techniques including bounds checking, proper input validation, and using safe arithmetic operations when handling file system size calculations. Organizations should also consider implementing network-based intrusion detection systems to monitor for exploitation attempts and maintain comprehensive system logging to track mount operations and potential exploitation attempts. The FreeBSD-specific note about privilege boundaries indicates that while the vulnerability may not cross privilege boundaries in that implementation, both systems require careful monitoring and patching to prevent potential escalation scenarios.