CVE-2011-1657 in PHP
Summary
by MITRE
The (1) ZipArchive::addGlob and (2) ZipArchive::addPattern functions in ext/zip/php_zip.c in PHP 5.3.6 allow context-dependent attackers to cause a denial of service (application crash) via certain flags arguments, as demonstrated by (a) GLOB_ALTDIRFUNC and (b) GLOB_APPEND.
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability identified as CVE-2011-1657 affects the PHP zip extension and represents a denial of service weakness that can be exploited through improper handling of specific flag arguments within the ZipArchive::addGlob and ZipArchive::addPattern functions. This issue exists within the ext/zip/php_zip.c source file of PHP version 5.3.6 and demonstrates how seemingly benign parameter validation can lead to application instability. The vulnerability is classified as context-dependent, meaning that exploitation requires specific conditions or arguments that trigger the flawed code path within the zip extension implementation.
The technical flaw manifests when the ZipArchive::addGlob and ZipArchive::addPattern functions receive certain flag arguments such as GLOB_ALTDIRFUNC and GLOB_APPEND. These flags are typically used with glob pattern matching functions to modify directory traversal behavior, but in the context of PHP's zip extension, they cause memory management issues that result in application crashes. The vulnerability stems from insufficient validation of these flag parameters within the zip extension's internal processing logic, leading to improper memory allocation or access patterns that ultimately cause the PHP application to terminate unexpectedly.
From an operational perspective, this vulnerability presents a significant risk to web applications that utilize PHP's zip functionality, particularly those that process user-supplied data through zip archive operations. Attackers can craft malicious inputs containing specific flag combinations that will trigger the denial of service condition, effectively rendering the targeted application unavailable to legitimate users. The impact extends beyond simple service interruption as it can be leveraged in broader attack scenarios where repeated exploitation could lead to resource exhaustion or application instability that affects system availability and user experience. This vulnerability is particularly concerning in shared hosting environments or applications that handle untrusted input through zip operations.
The flaw aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a form of improper input validation that can lead to memory corruption issues. From an ATT&CK framework perspective, this vulnerability could be categorized under T1499.004 for Network Denial of Service and potentially T1595.001 for Scanning for Vulnerabilities, as attackers may first identify systems running vulnerable PHP versions before attempting exploitation. Mitigation strategies include immediate patching of PHP installations to versions that address this vulnerability, implementing input validation controls to sanitize flag arguments before processing, and deploying application-level firewalls or intrusion prevention systems that can detect and block malicious flag combinations. Additionally, organizations should consider implementing monitoring solutions that can detect application crashes or unusual resource consumption patterns that might indicate exploitation attempts.