CVE-2018-20451 in libdoc
Summary
by MITRE
The process_file function in reader.c in libdoc through 2017-10-23 has a heap-based buffer over-read that allows attackers to cause a denial of service (application crash) via a crafted file.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/24/2020
The vulnerability identified as CVE-2018-20451 resides within the libdoc library, specifically in the process_file function located in reader.c. This issue represents a heap-based buffer over-read that occurs when processing crafted input files, fundamentally compromising the library's ability to handle malformed data gracefully. The vulnerability affects all versions of libdoc up to and including the 2017-10-23 release, creating a window of exposure for systems that rely on this document processing library for file interpretation and data extraction.
The technical flaw manifests when the process_file function attempts to read data from a heap-allocated buffer without proper bounds checking or validation of input file structures. This over-read condition allows an attacker to craft a specially formatted file that, when processed by the library, causes the application to access memory locations beyond the allocated buffer boundaries. The flaw operates at the memory management level where insufficient boundary validation permits unauthorized memory access patterns that ultimately lead to application instability and crash conditions.
From an operational impact perspective, this vulnerability creates a significant denial of service risk for applications that depend on libdoc for document processing capabilities. Attackers can exploit this weakness by preparing malicious files that trigger the buffer over-read condition, resulting in application crashes that disrupt normal service operations. The vulnerability's severity is amplified by its potential for remote exploitation, as attackers can deliver malicious files through various attack vectors including email attachments, web downloads, or file sharing systems without requiring special privileges or authentication.
The vulnerability aligns with CWE-125, which describes "Unspecified Other" buffer over-read conditions, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for "Endpoint Denial of Service" through resource exhaustion or application instability. The heap-based nature of the over-read indicates that attackers can potentially manipulate memory layout patterns to cause more severe consequences than simple application crashes. Organizations using affected versions of libdoc should prioritize immediate patching or mitigation strategies to prevent exploitation.
Mitigation strategies should include immediate deployment of the patched version of libdoc released after the 2017-10-23 timeframe, along with implementing input validation measures that restrict file processing to known good formats. Additionally, system administrators should consider implementing file type validation and sandboxing mechanisms for document processing workflows. Network-level controls such as intrusion detection systems can help detect attempts to exploit this vulnerability by monitoring for suspicious file processing patterns or malformed input sequences that might indicate exploitation attempts.