CVE-2007-6754 in FreeBSD
Summary
by MITRE
The ipalloc function in libc/stdlib/malloc.c in jemalloc in libc for FreeBSD 6.4 and NetBSD does not properly allocate memory, which makes it easier for context-dependent attackers to perform memory-related attacks such as buffer overflows via a large size value, related to "integer rounding and overflow" errors.
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Analysis
by VulDB Data Team • 02/19/2019
The vulnerability described in CVE-2007-6754 represents a critical memory management flaw within the jemalloc implementation used in FreeBSD 6.4 and NetBSD operating systems. This issue specifically affects the ipalloc function located in libc/stdlib/malloc.c, which serves as a fundamental component for dynamic memory allocation in these systems. The flaw manifests when the system processes large size values during memory allocation requests, creating conditions that can be exploited by malicious actors to manipulate memory layout and execution flow. The vulnerability's classification as context-dependent means that exploitation requires specific circumstances and attacker-controlled inputs that trigger the problematic code path within the memory allocator.
The technical root cause of this vulnerability stems from integer rounding and overflow errors that occur during memory allocation calculations. When the ipalloc function processes large memory size requests, the integer arithmetic operations fail to properly handle overflow conditions, resulting in incorrect memory block sizing calculations. This miscalculation can lead to scenarios where the allocated memory region is smaller than requested, creating potential buffer overflow conditions or memory corruption vulnerabilities. The flaw operates at the intersection of integer arithmetic handling and memory management, where the system's inability to properly validate and handle large integer values during allocation creates exploitable conditions. This type of vulnerability is categorized under CWE-191 as Integer Underflow (Wrap or Wraparound) and also relates to CWE-190 as Integer Overflow or Wraparound, both of which are fundamental weaknesses in computational systems.
The operational impact of CVE-2007-6754 extends beyond simple memory corruption, as it enables attackers to perform sophisticated memory-related attacks that can compromise system integrity and availability. Context-dependent attackers can leverage this vulnerability by crafting specific large size values that trigger the integer overflow conditions, potentially leading to buffer overflows that allow code execution or denial of service conditions. The attack surface is particularly concerning because it targets the core memory allocation routines that are utilized throughout the operating system and applications. This vulnerability can be exploited to bypass security mechanisms such as stack canaries, address space layout randomization, and other memory protection features, making it a significant threat to system security. The impact aligns with ATT&CK technique T1055.011 as "Process Injection: Dynamic-link Library Injection" and T1499.004 as "Network Denial of Service: Resource Exhaustion" where the memory corruption can enable further exploitation paths.
Mitigation strategies for CVE-2007-6754 require immediate system updates and patches from the respective operating system vendors, as the vulnerability exists in the core memory management libraries. System administrators should prioritize patching FreeBSD 6.4 and NetBSD installations to receive updated jemalloc implementations that properly handle integer overflow conditions during memory allocation. Additionally, implementing proper input validation and size checking mechanisms at application level can help reduce the attack surface, though this does not address the root cause within the system libraries. Network-level protections such as firewalls and intrusion detection systems can help monitor for exploitation attempts, while runtime protections like stack canaries and address space layout randomization provide additional defense layers. Organizations should also conduct comprehensive vulnerability assessments to identify applications that might be vulnerable to this type of memory corruption and implement proper memory management practices throughout their software development lifecycle. The fix typically involves implementing proper integer overflow checks and ensuring that memory allocation calculations handle large values correctly, preventing the wraparound conditions that lead to incorrect memory sizing.