CVE-2019-19630 in HTMLDOC
Summary
by MITRE
HTMLDOC 1.9.7 allows a stack-based buffer overflow in the hd_strlcpy() function in string.c (when called from render_contents in ps-pdf.cxx) via a crafted HTML document.
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Analysis
by VulDB Data Team • 03/09/2024
The vulnerability identified as CVE-2019-19630 represents a critical stack-based buffer overflow flaw within HTMLDOC version 1.9.7, specifically manifesting in the hd_strlcpy() function located in the string.c file. This vulnerability occurs when the function is invoked from the render_contents() method in ps-pdf.cxx, creating a pathway for malicious exploitation through carefully crafted HTML documents. The flaw stems from inadequate input validation and bounds checking within the string handling mechanism, allowing attackers to overwrite adjacent stack memory locations with controlled data.
The technical implementation of this vulnerability leverages the inherent properties of stack memory management and buffer handling in C-based applications. When HTMLDOC processes HTML documents containing maliciously constructed input, the hd_strlcpy() function fails to properly validate the length of source data against the destination buffer capacity. This oversight creates a condition where arbitrary data can be written beyond the allocated buffer boundaries, potentially corrupting stack metadata, return addresses, or adjacent variables. The vulnerability is particularly concerning because it operates within the core rendering pipeline of the application, meaning any HTML document processed by HTMLDOC could serve as a vector for exploitation.
The operational impact of this vulnerability extends beyond simple memory corruption, as it presents attackers with opportunities for arbitrary code execution and privilege escalation within the context of the HTMLDOC application. When successfully exploited, the buffer overflow could allow malicious actors to inject and execute arbitrary code on systems running vulnerable versions of HTMLDOC, potentially leading to complete system compromise. The attack surface is significant since HTMLDOC is commonly used for converting HTML documents to PDF or PostScript formats, making it a target for attackers who might distribute malicious HTML documents designed to exploit this vulnerability during routine document processing operations.
Security professionals should recognize this vulnerability as aligning with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions. The flaw also maps to ATT&CK technique T1203 Exploitation for Client Execution, as it enables attackers to execute malicious code through compromised applications. Mitigation strategies should focus on immediate patching of HTMLDOC to version 1.9.8 or later, which contains the necessary fixes for the buffer overflow condition. Additionally, organizations should implement strict input validation measures, deploy application whitelisting policies, and consider sandboxing HTMLDOC processes to limit potential damage from successful exploitation attempts. Network-based detection measures should monitor for suspicious HTML document processing activities that might indicate exploitation attempts, while regular security assessments should verify that no vulnerable instances remain operational within the environment.