CVE-2016-6297 in macOS
Summary
by MITRE
Integer overflow in the php_stream_zip_opener function in ext/zip/zip_stream.c in PHP before 5.5.38, 5.6.x before 5.6.24, and 7.x before 7.0.9 allows remote attackers to cause a denial of service (stack-based buffer overflow) or possibly have unspecified other impact via a crafted zip:// URL.
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Analysis
by VulDB Data Team • 09/20/2022
The vulnerability CVE-2016-6297 represents a critical integer overflow flaw within PHP's zip stream handling mechanism that affects multiple versions of the PHP runtime environment. This vulnerability resides in the php_stream_zip_opener function located in the ext/zip/zip_stream.c source file, making it accessible through the zip:// URL wrapper functionality that PHP provides for accessing zip archive contents. The flaw manifests when PHP processes specially crafted zip:// URLs, creating a dangerous condition that can lead to stack-based buffer overflows and potentially more severe security implications.
The technical nature of this vulnerability stems from improper input validation and integer overflow handling within the zip archive parsing logic. When PHP encounters a malformed zip archive URL, the integer overflow occurs during the calculation of buffer sizes needed to process the archive contents. This overflow can cause the application to allocate insufficient memory buffers, leading to stack corruption when the system attempts to write data beyond the allocated boundaries. The vulnerability is particularly dangerous because it can be triggered remotely through web applications that utilize the zip:// wrapper without proper input sanitization, allowing attackers to craft malicious URLs that exploit this condition.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attacks. While the primary effect is a stack-based buffer overflow that can cause application crashes and denial of service, the integer overflow condition creates opportunities for memory corruption that could theoretically be exploited to execute arbitrary code. Attackers can leverage this vulnerability to craft malicious zip archive URLs that, when processed by vulnerable PHP applications, trigger the buffer overflow condition. The vulnerability affects a wide range of PHP versions including 5.5.37 and earlier, 5.6.23 and earlier, and 7.0.8 and earlier, making it a significant concern for organizations running legacy PHP installations.
Security professionals should note that this vulnerability aligns with CWE-190, which describes integer overflow conditions that can lead to buffer overflows and memory corruption. The attack vector follows patterns consistent with ATT&CK technique T1190, which involves exploiting vulnerabilities in applications to achieve remote code execution or denial of service. Organizations should prioritize immediate patching of affected PHP installations to address this vulnerability, as the integer overflow creates a predictable exploitation pathway that can be automated. Additionally, implementing proper input validation and sanitization for all zip:// URL processing within applications can provide defensive measures against exploitation attempts. The vulnerability demonstrates the critical importance of proper integer handling in security-sensitive code paths, particularly in libraries that process untrusted data from network sources.