CVE-2016-4292 in Office
Summary
by MITRE
When opening a Hangul HShow Document (.hpt) and processing a structure within the document, Hancom Office 2014 will use a static size to allocate a heap buffer yet explicitly trust a size from the file when modifying data inside of it. Due to this, an aggressor can corrupt memory outside the bounds of this buffer which can lead to code execution under the context of the application.
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Analysis
by VulDB Data Team • 04/20/2025
The vulnerability identified as CVE-2016-4292 represents a classic heap buffer overflow flaw within Hancom Office 2014's processing of Hangul HShow Document files with the .hpt extension. This issue stems from a fundamental mismatch between static buffer allocation and dynamic size parameters extracted from maliciously crafted input files. The flaw occurs during the document parsing phase when the application initializes a fixed-size heap buffer but subsequently relies on size indicators embedded within the document structure to determine how much data to write into that buffer. This design pattern creates a scenario where an attacker-controlled size value can exceed the pre-allocated buffer boundaries, leading to memory corruption that can be exploited for arbitrary code execution.
The technical exploitation of this vulnerability aligns with common software security principles and maps directly to CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The vulnerability demonstrates a failure in input validation and memory management practices, where the application trusts external data without proper sanitization or size verification. When processing the .hpt file structure, the application allocates memory based on a predetermined static size while simultaneously reading and trusting a size field from the file header. This discrepancy allows an attacker to craft a malicious document that specifies a size larger than the allocated buffer, enabling them to overwrite adjacent memory regions including return addresses, function pointers, or other critical control data structures.
From an operational perspective, this vulnerability presents a significant risk to organizations using Hancom Office 2014, as it can be exploited through social engineering techniques involving malicious document attachments. The attack requires minimal user interaction beyond opening the malicious file, making it particularly dangerous in targeted phishing campaigns or supply chain attacks. The code execution occurs within the application context, potentially allowing attackers to escalate privileges or execute arbitrary commands with the same permissions as the office application. This vulnerability also aligns with ATT&CK technique T1204.002, which involves user execution of malicious files, and T1059, covering command and scripting interpreter usage for execution. The exploitation process typically involves crafting a specially formatted .hpt file that triggers the buffer overflow condition during normal document processing, potentially leading to complete system compromise.
The mitigation strategies for this vulnerability encompass multiple layers of defense including immediate patching of Hancom Office 2014 to address the buffer overflow condition, implementing strict file validation policies for document processing, and deploying application whitelisting controls to prevent execution of untrusted files. Organizations should also consider network-based protections such as email filtering and web proxy configurations that can block or quarantine suspicious .hpt files. Additionally, regular security awareness training for users can help reduce the risk of successful exploitation through social engineering. The vulnerability underscores the critical importance of proper input validation and memory management practices in office productivity software, where the combination of user trust and application functionality creates an ideal attack surface for memory corruption exploits. Security professionals should also monitor for similar patterns in other office applications and ensure comprehensive testing of file parsing routines to prevent analogous vulnerabilities from being introduced in future software releases.