CVE-2019-11047 in PHP
Summary
by MITRE
When PHP EXIF extension is parsing EXIF information from an image, e.g. via exif_read_data() function, in PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13 and 7.4.0 it is possible to supply it with data what will cause it to read past the allocated buffer. This may lead to information disclosure or crash.
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Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2019-11047 represents a critical buffer overread flaw within PHP's EXIF extension that affects multiple PHP version streams including 7.2.x below 7.2.26, 7.3.x below 7.3.13, and 7.4.0. This issue occurs when the exif_read_data() function processes EXIF metadata from image files, creating a scenario where maliciously crafted EXIF data can cause the extension to access memory beyond allocated boundaries. The vulnerability stems from insufficient input validation and boundary checking within the EXIF parsing routine, allowing attackers to manipulate the parsing process through specially crafted image files containing malformed EXIF metadata. The flaw is categorized under CWE-125 as an out-of-bounds read, which represents a fundamental memory safety issue that can be exploited to extract sensitive information from adjacent memory locations or cause application crashes.
The technical exploitation of this vulnerability involves crafting EXIF data that tricks the parsing logic into reading beyond the intended buffer limits, potentially exposing sensitive data such as stack contents, heap information, or other memory segments that may contain credentials, session tokens, or other confidential information. When the EXIF extension encounters malformed data during parsing, it fails to properly validate the bounds of the data being read, leading to memory access violations that can result in information disclosure or denial of service conditions. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution, as attackers could leverage the information disclosure to gather system information for further exploitation. The impact extends beyond simple crashes to include potential data leakage that could compromise system security and confidentiality.
The operational impact of CVE-2019-11047 is significant for web applications that process user-uploaded images through PHP's EXIF extension, particularly in environments where image handling is a common functionality such as social media platforms, content management systems, or file upload services. Attackers can exploit this vulnerability by uploading maliciously crafted images that contain specially formatted EXIF data, leading to information disclosure or application instability. The vulnerability affects not only direct execution but also indirect impacts through memory corruption that could potentially lead to more severe exploitation scenarios. Organizations running affected PHP versions are at risk of unauthorized information disclosure, service disruption, and potential escalation to more critical system compromises. The vulnerability demonstrates the importance of proper input validation and memory safety practices in extension libraries that handle untrusted data from user inputs.
Mitigation strategies for CVE-2019-11047 primarily focus on upgrading to patched PHP versions where the buffer overread issue has been resolved through proper bounds checking and input validation. System administrators should prioritize patching affected installations and implementing additional security controls such as image validation that strips EXIF metadata from uploaded files when possible. The implementation of proper input sanitization and validation at multiple layers including web application firewalls and file upload validation can provide additional defense in depth. Organizations should also consider implementing monitoring for suspicious file upload activities and conducting regular security assessments of image processing functionalities to identify potential exploitation vectors. The vulnerability highlights the critical need for maintaining up-to-date software components and implementing robust security practices in web application development environments.