CVE-2018-8378 in Office
Summary
by MITRE
An information disclosure vulnerability exists when Microsoft Office software reads out of bound memory due to an uninitialized variable, which could disclose the contents of memory, aka "Microsoft Office Information Disclosure Vulnerability." This affects Word, Microsoft SharePoint Server, Microsoft Office Word Viewer, Microsoft Excel Viewer, Microsoft SharePoint, Microsoft Office.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2018-8378 represents a critical information disclosure flaw within Microsoft Office software components that stems from improper handling of memory operations during document processing. This issue specifically manifests when the affected applications encounter malformed or specially crafted Office documents that trigger out-of-bounds memory access patterns. The root cause lies in the presence of an uninitialized variable within the memory management routines of these applications, which creates predictable memory access patterns that can be exploited by malicious actors to extract sensitive information from the application's memory space. The vulnerability affects multiple Microsoft Office products including Word, Excel Viewer, SharePoint Server, and various Office Viewer applications, making it particularly dangerous due to its widespread impact across the Microsoft Office ecosystem.
The technical exploitation of this vulnerability occurs when Microsoft Office applications process maliciously crafted documents that contain malformed data structures. During the parsing process, the uninitialized variable leads to unpredictable memory access patterns where the application attempts to read memory locations that have not been properly initialized with valid data. This creates opportunities for attackers to craft specific document payloads that cause the application to inadvertently expose memory contents, including sensitive data such as encryption keys, passwords, or other confidential information stored in memory. The out-of-bounds memory read operations can be leveraged to extract information from adjacent memory locations, potentially revealing system information, application state data, or even portions of other running processes. This type of vulnerability falls under CWE-457: Use of Uninitialized Variable, which is classified as a fundamental memory safety issue that can lead to information disclosure, denial of service, or potentially more severe exploitation vectors.
The operational impact of CVE-2018-8378 extends beyond simple information disclosure, as it can serve as a stepping stone for more sophisticated attacks within targeted environments. When successful, this vulnerability can provide attackers with access to memory contents that may contain sensitive data such as session tokens, user credentials, or cryptographic material that could be used to escalate privileges or maintain persistent access to compromised systems. The vulnerability's presence in SharePoint Server components particularly amplifies its impact, as it can be exploited in web-based attacks where attackers craft malicious documents hosted on SharePoint servers that are then opened by unsuspecting users. The attack vector typically involves social engineering campaigns where users are tricked into opening malicious Office documents through phishing emails or compromised websites, making this vulnerability particularly dangerous in enterprise environments where document sharing and collaboration are common practices.
Mitigation strategies for CVE-2018-8378 should prioritize immediate patch deployment from Microsoft, as the vendor released security updates specifically addressing this vulnerability through their regular security bulletin process. Organizations should implement defensive measures including email filtering and content inspection to prevent malicious documents from reaching end users, particularly focusing on Office document attachments that may contain suspicious elements. Network-based protections can include implementing strict file type restrictions and content validation for Office documents within enterprise environments, while endpoint protection solutions should be configured to monitor for suspicious memory access patterns. Security teams should also consider implementing application whitelisting policies that restrict execution of Office applications in potentially untrusted contexts, and establish monitoring procedures to detect anomalous memory access behaviors that may indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1059.005 for command and scripting interpreter suggests that attackers may also leverage information disclosure to gain additional footholds within compromised systems, making comprehensive monitoring and incident response procedures essential for organizations that have not yet patched their systems.