CVE-2018-5201 in Office 2010
Summary
by MITRE
Hancom Office 2018 10.0.0.8214 and earlier, Hancom Office NEO 9.6.1.10472 and earlier, Hancom Office 2014 9.1.1.4540 and earlier, Hancom Office 2010 8.5.8.1724 and earlier versions have a heap overflow vulnerability when handling Compound File in document. This result in a program crash or denial of service conditions.
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Analysis
by VulDB Data Team • 04/23/2020
The heap overflow vulnerability identified in CVE-2018-5201 affects multiple versions of Hancom Office software including Hancom Office 2018, Hancom Office NEO, Hancom Office 2014, and Hancom Office 2010. This vulnerability specifically manifests when the affected applications process Compound File Binary Format (CFBF) documents, which are commonly used for storing complex office documents containing multiple streams of data. The flaw represents a critical security weakness that can be exploited by malicious actors to disrupt normal application operations. The vulnerability stems from inadequate bounds checking during the parsing of Compound File structures, allowing attackers to manipulate memory allocation processes through specially crafted malicious documents. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a serious memory corruption vulnerability that can lead to arbitrary code execution or system instability. The ATT&CK framework categorizes this as a memory corruption vulnerability that can be leveraged for privilege escalation and system compromise.
The technical implementation of this heap overflow occurs when Hancom Office applications attempt to parse Compound File Binary Format documents without proper validation of input data structures. During document processing, the application allocates heap memory to store data from the compound file, but fails to validate the size parameters or boundaries of the data being read from the document. When an attacker crafts a malicious document with oversized or malformed data structures within the compound file, the application's memory management routines become overwhelmed, leading to heap corruption. This memory corruption can manifest as immediate program crashes, denial of service conditions, or in more severe cases, allow for remote code execution if the attacker can control the memory layout. The vulnerability is particularly dangerous because Compound File Binary Format is a widely used document format that supports complex data structures including embedded objects, images, and other multimedia content, providing multiple vectors for exploitation.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it represents a significant threat to organizational security infrastructure. When exploited, this vulnerability can disrupt business operations by causing critical office applications to crash, potentially leading to data loss or service interruptions. Organizations using affected Hancom Office versions may experience cascading failures if the vulnerability is exploited in a networked environment where these applications are used to process documents from external sources. The vulnerability's exploitation requires minimal technical expertise, making it attractive to threat actors who may use it as part of broader attack campaigns. Additionally, the widespread adoption of Hancom Office in various sectors including government, financial services, and enterprise environments increases the potential impact of this vulnerability across multiple threat scenarios. The vulnerability can be particularly dangerous in environments where document processing is automated or where users frequently open documents from untrusted sources.
Mitigation strategies for CVE-2018-5201 should focus on immediate software updates and implementation of defensive measures. Organizations should prioritize updating to the latest versions of Hancom Office that contain patches addressing this heap overflow vulnerability, as these updates typically include proper bounds checking and memory validation routines. Network segmentation and document filtering should be implemented to prevent potentially malicious documents from reaching end-user systems, particularly in environments where users process documents from external sources. Input validation should be enforced at multiple levels including application-level parsing, network-level filtering, and endpoint protection solutions. Security monitoring should be enhanced to detect unusual application behavior patterns that may indicate exploitation attempts, such as unexpected memory allocation patterns or application crashes. System hardening measures including address space layout randomization and data execution prevention should be enabled to reduce the effectiveness of potential exploitation attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other office productivity applications and document processing systems within the organization's infrastructure.