CVE-2014-3669 in PHP
Summary
by MITRE
Integer overflow in the object_custom function in ext/standard/var_unserializer.c in PHP before 5.4.34, 5.5.x before 5.5.18, and 5.6.x before 5.6.2 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via an argument to the unserialize function that triggers calculation of a large length value.
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Analysis
by VulDB Data Team • 02/23/2022
The vulnerability identified as CVE-2014-3669 represents a critical integer overflow flaw within PHP's serialization handling mechanism that affects multiple versions of the PHP interpreter. This issue resides in the object_custom function located in the ext/standard/var_unserializer.c source file, which processes serialized data during the unserialize operation. The vulnerability manifests when an attacker crafts malicious serialized data containing an argument that triggers an incorrect calculation of a large length value during deserialization. This flaw falls under the CWE-190 category of Integer Overflow or Wraparound, where arithmetic operations exceed the maximum representable value for the integer type, leading to unexpected behavior in the application's memory management and execution flow.
The technical exploitation of this vulnerability occurs through the manipulation of serialized data structures that are processed by PHP's unserialize function. When the object_custom function attempts to calculate a length value during deserialization, an integer overflow occurs that can result in either a buffer overflow condition or a memory corruption scenario. This overflow can cause the application to crash due to invalid memory access patterns or potentially allow for arbitrary code execution if the overflowed value is used in memory allocation or indexing operations. The vulnerability is particularly dangerous because it can be triggered through user-supplied input that passes through the unserialize function, making it exploitable via web applications that accept serialized data from external sources.
The operational impact of CVE-2014-3669 extends beyond simple denial of service scenarios to potentially enable remote code execution in vulnerable environments. Attackers can craft serialized payloads that, when processed by affected PHP versions, cause the application to behave unpredictably and potentially execute malicious code with the privileges of the web server process. This vulnerability affects a wide range of PHP installations including versions 5.4.33 and earlier, 5.5.17 and earlier, and 5.6.1 and earlier, making it a widespread concern for web application security. The vulnerability aligns with ATT&CK technique T1190 for Exploit Public-Facing Application, as it represents a remote exploitation vector that can be leveraged through web application interfaces.
Organizations affected by this vulnerability should implement immediate mitigation strategies including upgrading to patched PHP versions where available. The recommended remediation involves updating to PHP 5.4.34, 5.5.18, or 5.6.2 respectively, which contain the necessary fixes to prevent integer overflow conditions during serialization processing. Additionally, administrators should consider implementing input validation and sanitization measures to prevent untrusted data from reaching the unserialize function, particularly when processing user-supplied serialized content. Security monitoring should be enhanced to detect unusual patterns in serialization operations that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper integer handling in security-critical code sections and highlights the need for comprehensive testing of serialization mechanisms against boundary conditions and malicious inputs.