CVE-2018-16438 in HDF5
Summary
by MITRE
An issue was discovered in the HDF HDF5 1.8.20 library. There is an out of bounds read in H5L_extern_query at H5Lexternal.c.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/20/2020
The vulnerability identified as CVE-2018-16438 represents a critical out-of-bounds read condition within the HDF HDF5 1.8.20 library, specifically affecting the H5L_extern_query function located in the H5Lexternal.c source file. This issue arises from improper bounds checking during the processing of external link data structures, creating a scenario where the library attempts to access memory locations beyond the allocated buffer boundaries. The flaw manifests when the library handles external symbolic links within HDF5 files, particularly during the query operation that retrieves information about external links. Such out-of-bounds memory access can lead to unpredictable behavior including application crashes, data corruption, or potential information disclosure. The vulnerability stems from a classic programming error where the code does not adequately validate the size or bounds of data structures before performing memory operations, making it susceptible to exploitation through malformed input files. This type of vulnerability falls under CWE-129, which specifically addresses insufficient validation of length of input buffers, and represents a fundamental flaw in the library's input validation mechanisms. The impact extends beyond simple program termination as it can potentially enable attackers to extract sensitive information from memory or cause denial of service conditions that affect applications relying on HDF5 file processing. The vulnerability is particularly concerning in environments where HDF5 files are processed from untrusted sources, as it can be leveraged to craft malicious files that trigger the out-of-bounds read condition during normal library operation. Security researchers have classified this issue as a high-severity vulnerability due to its potential for exploitation in various attack scenarios including remote code execution when combined with other vulnerabilities. The flaw demonstrates poor defensive programming practices and highlights the importance of robust input validation and bounds checking in security-critical libraries. Organizations utilizing HDF5 libraries for data storage and retrieval must understand that this vulnerability can affect any application that processes external links within HDF5 files, particularly in scientific computing environments where such files are commonly used for data exchange and storage. The vulnerability's exploitation requires careful crafting of external link data structures that can trigger the specific code path in H5Lexternal.c, making it somewhat more complex than simpler buffer overflow conditions but still highly impactful. This issue affects a wide range of applications including scientific data analysis tools, data visualization software, and storage systems that rely on HDF5 format for data management and exchange. The out-of-bounds read condition creates opportunities for attackers to manipulate memory access patterns and potentially gain insights into the application's memory layout. The vulnerability's presence in the external link processing functionality indicates that the issue is not limited to simple file reading operations but extends to the library's ability to handle complex metadata structures within HDF5 files. Proper mitigation requires updating to patched versions of the HDF5 library where bounds checking has been implemented to prevent access beyond valid buffer boundaries. Additionally, input sanitization and validation should be implemented at application layers that process HDF5 files to reduce the attack surface. The vulnerability underscores the necessity of thorough code review and testing procedures, particularly for libraries that handle complex binary formats and are widely used across different software ecosystems. Organizations should implement monitoring and logging mechanisms to detect potential exploitation attempts and establish secure coding practices that prevent similar issues in future development cycles. The ATT&CK framework categorizes this vulnerability under privilege escalation and defense evasion techniques, as it can be used to manipulate application behavior and potentially bypass security controls. This flaw demonstrates the critical importance of maintaining up-to-date security patches and implementing proper input validation across all components of software systems that process external data formats.