CVE-2016-3283 in Word Viewer
Summary
by MITRE
Microsoft Word Viewer allows remote attackers to execute arbitrary code via a crafted Office document, aka "Microsoft Office Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 09/01/2022
The vulnerability identified as CVE-2016-3283 represents a critical memory corruption flaw within Microsoft Word Viewer that enables remote code execution through maliciously crafted Office documents. This vulnerability specifically affects versions of Microsoft Word Viewer that are installed on Windows systems, making it particularly dangerous in enterprise environments where legacy document viewing capabilities are still utilized. The flaw stems from improper handling of memory structures when processing certain Office document formats, creating opportunities for attackers to inject and execute malicious code without user interaction. This type of vulnerability is classified under CWE-125 as "Out-of-bounds Read" and aligns with ATT&CK technique T1203 for "Exploitation for Client Execution" which targets applications that process untrusted data from remote sources.
The technical implementation of this vulnerability occurs when Word Viewer processes malformed Office documents that contain specially crafted data structures designed to trigger memory corruption during document rendering. Attackers can exploit this by embedding malicious code within seemingly legitimate Office files such as .doc, .docx, or .rtf documents. When a user opens such a document with Word Viewer, the vulnerable code path is triggered, causing memory corruption that can be leveraged to execute arbitrary code with the privileges of the user running the viewer application. The memory corruption typically manifests as stack or heap corruption that allows attackers to overwrite critical memory locations, potentially leading to complete system compromise. This vulnerability is particularly concerning because Word Viewer is often installed on systems that do not receive regular updates, creating persistent attack vectors that remain unpatched for extended periods.
The operational impact of CVE-2016-3283 extends beyond immediate code execution capabilities to encompass broader security implications for enterprise networks. Organizations that continue to support Word Viewer installations face significant risk exposure, as the vulnerability can be exploited through email attachments, web downloads, or file transfers without requiring any user interaction beyond opening the malicious document. This makes it particularly effective for phishing campaigns and targeted attacks where social engineering is minimized. The vulnerability affects not only individual endpoints but can also serve as a foothold for lateral movement within networks, especially when combined with other exploitation techniques. Security professionals must consider the prevalence of Word Viewer installations in legacy systems and the potential for privilege escalation attacks that could result in domain-level compromise.
Mitigation strategies for CVE-2016-3283 should prioritize immediate patching of all affected Microsoft Word Viewer installations through official Microsoft security updates. Organizations should implement comprehensive network monitoring to detect attempts to access or open suspicious Office documents, particularly those with unusual file extensions or embedded objects. Disabling Word Viewer functionality on systems where it is not required, or removing it entirely from the system, provides an effective defense mechanism against exploitation attempts. Network segmentation and application whitelisting policies can further reduce attack surface by preventing execution of unauthorized Office document processing applications. Additionally, user education programs should emphasize the importance of avoiding suspicious email attachments and verifying document sources before opening potentially malicious files. Security teams should also consider implementing sandboxing solutions for document processing and maintaining detailed audit logs of Word Viewer usage to detect anomalous behavior patterns that may indicate exploitation attempts.