CVE-2005-1043 in Mac OS X
Summary
by MITRE
exif.c in PHP before 4.3.11 allows remote attackers to cause a denial of service (memory consumption and crash) via an EXIF header with a large IFD nesting level, which causes significant stack recursion.
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Analysis
by VulDB Data Team • 05/31/2019
The vulnerability described in CVE-2005-1043 represents a critical denial of service weakness in PHP's handling of EXIF image metadata processing. This issue affects PHP versions prior to 4.3.11 and stems from improper validation of EXIF headers during image processing operations. The flaw specifically manifests when PHP encounters EXIF data containing deeply nested IFD (Image File Directory) structures, which trigger excessive stack recursion during parsing operations. The vulnerability operates at the intersection of image processing libraries and memory management within the PHP runtime environment, creating a scenario where maliciously crafted EXIF data can overwhelm system resources and cause application instability.
The technical implementation of this vulnerability exploits the recursive parsing mechanism used by PHP's exif.c module to traverse IFD structures within EXIF metadata. When an attacker supplies an EXIF header with an excessive nesting level, the parsing function recursively calls itself to process each nested directory entry, consuming stack memory at an exponential rate. This recursive traversal continues until the system stack overflows, leading to either application crashes or complete system resource exhaustion. The vulnerability demonstrates characteristics consistent with CWE-674, which addresses improper control of recursion depth, and can be categorized under the broader category of stack-based buffer overflows. The attack vector requires only the submission of specially crafted EXIF data to a PHP application that processes image metadata, making it particularly dangerous in web applications that accept user-uploaded images.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire web server operations. When exploited, the denial of service condition can cause PHP processes to consume all available stack memory, leading to application crashes that may affect multiple concurrent users. In web server environments, this vulnerability can be leveraged to exhaust system resources and cause cascading failures across multiple application instances. The vulnerability is particularly concerning in environments where PHP applications handle user-generated content, as attackers can craft malicious EXIF data that appears legitimate to image processing libraries while simultaneously causing system instability. This attack pattern aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion, and represents a classic example of how image processing libraries can become attack vectors in web applications.
The recommended mitigation strategy focuses on immediate patching of affected PHP installations to versions 4.3.11 or later, where the recursive parsing logic has been modified to implement proper depth limits and stack management. Administrators should also implement input validation measures that restrict EXIF data processing or employ alternative image handling libraries that do not exhibit this recursive behavior. Additional defensive measures include implementing rate limiting on image upload operations, deploying monitoring systems to detect unusual memory consumption patterns, and configuring PHP with reduced stack size limits where possible. Security teams should also consider implementing automated scanning of uploaded image files for potentially malicious EXIF structures and establish incident response procedures for handling denial of service events related to image processing components. These measures address both the immediate vulnerability and help prevent similar issues in related image processing functionality.