CVE-2019-18218 in File
Summary
by MITRE
cdf_read_property_info in cdf.c in file through 5.37 does not restrict the number of CDF_VECTOR elements, which allows a heap-based buffer overflow (4-byte out-of-bounds write).
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Analysis
by VulDB Data Team • 01/17/2024
The vulnerability identified as CVE-2019-18218 resides within the file utility software version 5.37 and specifically affects the cdf_read_property_info function in the cdf.c module. This issue manifests as a heap-based buffer overflow that occurs when processing Compound Document File (CDF) format files. The flaw arises from the absence of proper bounds checking on the number of CDF_VECTOR elements that can be processed, creating a condition where an attacker can manipulate the input data to trigger an out-of-bounds write operation. The vulnerability is classified as a 4-byte out-of-bounds write, indicating that malicious input can cause data to be written beyond the allocated memory boundaries, potentially corrupting adjacent memory regions. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, which represents a fundamental weakness in input validation that allows attackers to manipulate array indices beyond their valid range.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates opportunities for arbitrary code execution within the context of the application processing the malicious CDF file. When an application processes a crafted CDF file containing an excessive number of CDF_VECTOR elements, the buffer overflow can overwrite adjacent memory locations, potentially allowing an attacker to manipulate program execution flow, inject malicious code, or cause application crashes. The heap-based nature of the overflow means that the vulnerability is particularly dangerous because heap memory management is complex and unpredictable, making exploitation more feasible and potentially more reliable than stack-based buffer overflows. This vulnerability directly relates to the ATT&CK technique T1059.007 for Command and Scripting Interpreter: Unix Shell, as it could enable an attacker to execute arbitrary commands if successful exploitation leads to code execution within the application context.
The root cause of this vulnerability stems from inadequate input validation and memory management practices within the file utility's CDF parsing implementation. The cdf_read_property_info function fails to enforce reasonable limits on the number of vector elements that can be processed, allowing maliciously crafted input to bypass normal bounds checking mechanisms. This represents a classic case of insufficient input sanitization where the software assumes that input data from external sources will conform to expected formats without proper validation. The vulnerability demonstrates a lack of defensive programming practices that should include bounds checking, input length validation, and proper memory allocation controls. Security practitioners should note that this vulnerability affects not just the specific file utility version mentioned but potentially any system that relies on similar CDF parsing libraries, making it a widespread concern for organizations that process compound document files. Organizations should implement immediate mitigations including updating to patched versions of the file utility, implementing input validation controls, and deploying intrusion detection systems that can identify attempts to exploit this vulnerability through malformed CDF files.