CVE-2005-1042 in PHP
Summary
by MITRE
Integer overflow in the exif_process_IFD_TAG function in exif.c in PHP before 4.3.11 may allow remote attackers to execute arbitrary code via an IFD tag that leads to a negative byte count.
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Analysis
by VulDB Data Team • 06/04/2019
The vulnerability identified as CVE-2005-1042 represents a critical integer overflow flaw within the PHP image processing library that affects versions prior to 4.3.11. This issue specifically resides in the exif_process_IFD_TAG function located in the exif.c source file, where improper handling of image file metadata can lead to severe security implications. The flaw occurs when processing IFD (Image File Directory) tags within EXIF metadata structures, creating conditions where arithmetic operations result in integer wraparound behavior that can be exploited by malicious actors.
The technical nature of this vulnerability stems from inadequate input validation and boundary checking within the EXIF processing code. When PHP encounters an IFD tag with malformed or specially crafted parameters, the processing function fails to properly validate the byte count values, leading to integer overflow conditions. This overflow results in negative byte count values that can cause memory allocation errors, buffer overflows, or other memory corruption issues. The vulnerability is classified under CWE-190 as an integer overflow or wraparound, specifically manifesting as an integer underflow in the context of memory allocation calculations.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to achieve remote code execution on affected systems. Attackers can craft malicious image files containing specially constructed EXIF metadata that triggers the integer overflow when PHP processes the image. This allows for arbitrary code execution with the privileges of the web server process, potentially leading to complete system compromise. The vulnerability is particularly dangerous in web environments where users can upload images, as it enables attackers to execute malicious code without requiring direct system access or authentication.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly focusing on code injection and privilege escalation techniques. Attackers can leverage this flaw as part of a broader attack chain to establish persistent access to compromised systems, often combined with other vulnerabilities to achieve full system compromise. The vulnerability demonstrates how seemingly benign image processing functionality can become a critical attack surface when proper input validation and memory management practices are not implemented.
Mitigation strategies for this vulnerability include immediate patching of PHP installations to versions 4.3.11 or later where the integer overflow has been corrected through proper boundary checking and input validation. Organizations should also implement strict file type validation and content scanning for uploaded images, particularly in web applications that process user-uploaded media. Additional defensive measures include running PHP with restricted privileges, implementing proper memory limits, and employing web application firewalls to detect and block malicious image uploads. Regular security audits and vulnerability assessments should be conducted to identify similar integer overflow conditions in other libraries and applications that process binary data structures.