CVE-2015-2810 in Word Viewer
Summary
by MITRE
Integer overflow in the HwpApp::CHncSDS_Manager function in Hancom Office HanWord processor, as used in Hwp 2014 VP before 9.1.0.2342, HanWord Viewer 2007 and Viewer 2010 8.5.6.1158, and HwpViewer 2014 VP 9.1.0.2186, allows remote attackers to cause a denial of service (crash) and possibly "influence the program's execution flow" via a document with a large paragraph size, which triggers heap corruption.
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Analysis
by VulDB Data Team • 06/30/2017
The vulnerability described in CVE-2015-2810 represents a critical integer overflow flaw within the Hancom Office HanWord processor software ecosystem. This vulnerability specifically affects multiple versions of Hancom's word processing applications including HanWord 2014 VP prior to 9.1.0.2342, HanWord Viewer 2007 and Viewer 2010 at version 8.5.6.1158, and HwpViewer 2014 VP at version 9.1.0.2186. The flaw exists within the HwpApp::CHncSDS_Manager function which handles document processing operations. The vulnerability demonstrates characteristics that align with CWE-190, Integer Overflow or Wraparound, where an application fails to properly handle integer values that exceed the maximum representable value for the given data type. This particular implementation flaw occurs when processing documents containing excessively large paragraph sizes, creating a scenario where the application's internal calculations fail to account for the boundaries of integer data types.
The technical exploitation of this vulnerability involves crafting malicious documents with oversized paragraph dimensions that trigger the integer overflow condition within the CHncSDS_Manager function. When the processor attempts to allocate memory or perform calculations based on these inflated paragraph size values, the integer overflow causes heap corruption in the application's memory management system. This heap corruption manifests as application crashes or denial of service conditions, effectively preventing legitimate users from accessing or processing documents. The vulnerability's potential to influence program execution flow indicates that attackers may be able to manipulate the application's memory state beyond simple crash conditions, potentially allowing for more sophisticated exploitation techniques. The flaw demonstrates how improper input validation and boundary checking in document parsing components can create security risks that extend beyond simple availability impacts.
From an operational perspective, this vulnerability presents significant risks to organizations relying on Hancom Office products for document processing tasks. The remote attack vector means that adversaries can exploit this flaw without requiring physical access to target systems, making it particularly dangerous in enterprise environments where document sharing occurs frequently. The vulnerability affects multiple product versions across different release lines, indicating a systemic issue within the application's document parsing architecture that required patching across various software releases. The potential for heap corruption and execution flow manipulation suggests that this vulnerability could serve as a stepping stone for more advanced attacks, particularly when combined with other exploitation techniques. Organizations using affected versions of Hancom Office products face risks of service disruption, data accessibility issues, and potential escalation opportunities for attackers who successfully exploit this vulnerability.
Mitigation strategies for CVE-2015-2810 should prioritize immediate software updates to versions that address the integer overflow condition in the CHncSDS_Manager function. System administrators should implement strict document validation policies that include size and format checks before processing potentially malicious content. Network segmentation and application whitelisting can help limit the impact of successful exploitation attempts by restricting access to vulnerable applications. The vulnerability's classification as a denial of service condition with potential for execution flow manipulation suggests that organizations should implement comprehensive monitoring for abnormal application behavior and memory allocation patterns. Additionally, regular security assessments of document processing applications should be conducted to identify similar integer overflow conditions that may exist in other components of the software ecosystem. The remediation approach should align with industry best practices for memory safety and input validation, ensuring that all integer operations include proper bounds checking and overflow detection mechanisms to prevent similar vulnerabilities from emerging in future software releases.