CVE-2016-4298 in Office
Summary
by MITRE
When opening a Hangul HShow Document (.hpt) and processing a structure within the document, Hancom Office 2014 will attempt to allocate space for a list of elements using a length from the file. When calculating this length, an integer overflow can be made to occur which will cause the buffer to be undersized when the application tries to copy file data into the object containing this structure. This allows one to overwrite contiguous data in the heap 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-2016-4298 represents a critical heap-based buffer overflow in Hancom Office 2014 that arises during the processing of Hangul HShow Document files with the .hpt extension. This flaw exists within the application's file parsing mechanism where it attempts to allocate memory for a list structure based on data extracted from the malicious file. The vulnerability stems from improper input validation and arithmetic handling during memory allocation calculations, creating a scenario where integer overflow conditions can be exploited by attackers to manipulate memory layout and execution flow.
The technical implementation of this vulnerability involves the application's handling of structured data within the .hpt file format, specifically when processing a list of elements that requires dynamic memory allocation. During this process, the software calculates the required buffer size using a value directly extracted from the file without proper bounds checking or overflow detection mechanisms. When the calculated length exceeds the maximum representable value for the integer type used in the allocation calculation, an integer overflow occurs that results in a significantly smaller buffer allocation than required. This undersized buffer creates a condition where subsequent memory copy operations will overwrite adjacent heap memory regions, potentially corrupting critical data structures or executable code.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables arbitrary code execution within the security context of the affected application. Attackers can craft malicious .hpt files that, when opened by an unsuspecting user, will trigger the integer overflow condition and allow for memory overwrite operations that can be carefully manipulated to inject and execute malicious code. This represents a severe privilege escalation vector since the executed code runs with the same privileges as the vulnerable Hancom Office application, potentially allowing attackers to gain unauthorized access to system resources, execute arbitrary commands, or establish persistent access to the compromised system. The vulnerability is particularly dangerous in enterprise environments where office productivity suites are widely deployed and users may inadvertently open malicious documents.
Mitigation strategies for CVE-2016-4298 should focus on immediate patch deployment from Hancom to address the integer overflow condition in memory allocation calculations. Organizations should implement strict file extension filtering and content validation for .hpt files, particularly in email gateways and file sharing systems. Network-based protections should include deep packet inspection rules that can identify and block suspicious .hpt file content patterns that may indicate exploitation attempts. From a defensive perspective, the vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and maps to ATT&CK technique T1059.007 for command and script interpreter execution. System administrators should also consider implementing application whitelisting policies that restrict execution of Hancom Office components to trusted environments and maintain comprehensive monitoring for anomalous memory allocation patterns or heap corruption indicators that may signal exploitation attempts.