CVE-2019-0801 in Office
Summary
by MITRE
A remote code execution vulnerability exists when Microsoft Office fails to properly handle certain files.To exploit the vulnerability, an attacker would have to convince a user to open a specially crafted URL file that points to an Excel or PowerPoint file that was also downloaded.The update addresses the vulnerability by correcting how Office handles these files., aka 'Office Remote Code Execution Vulnerability'.
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Analysis
by VulDB Data Team • 08/27/2023
This vulnerability represents a critical remote code execution flaw in Microsoft Office applications that stems from improper handling of specially crafted file references. The vulnerability specifically affects how Office processes certain URL files that point to Excel or PowerPoint documents, creating a dangerous attack vector that can be exploited through social engineering techniques. The flaw allows attackers to execute arbitrary code on target systems when users open maliciously crafted file references, making it particularly dangerous in enterprise environments where users frequently interact with external file sources.
The technical mechanism of exploitation involves the manipulation of URL file references that direct users to malicious Office documents stored on remote servers. When Office attempts to resolve these references, it fails to properly validate the file content, allowing attackers to inject malicious code that executes with the privileges of the logged-in user. This vulnerability operates at the intersection of file handling and network protocol processing, where Office's failure to implement proper input sanitization creates an execution path for attacker-controlled code. The flaw demonstrates poor defensive programming practices and inadequate validation of external references, aligning with CWE-129 which addresses improper validation of input.
From an operational impact perspective, this vulnerability enables attackers to achieve full system compromise without requiring user interaction beyond opening a malicious file reference. The attack requires minimal technical sophistication from threat actors, as it relies on social engineering to convince victims to open seemingly legitimate files. Once exploited, attackers can establish persistent access, escalate privileges, and potentially move laterally within networks. The vulnerability affects multiple Office applications including Excel and PowerPoint, amplifying its impact across different user workflows and increasing the attack surface for potential exploitation.
Security professionals should implement multiple layers of defense to mitigate this vulnerability, including email filtering to block suspicious URL references, network segmentation to limit lateral movement, and user education to recognize potentially malicious file interactions. The update provided by Microsoft addresses the core issue by implementing proper validation of file references and enhancing the handling of external content within Office applications. Organizations should prioritize immediate patch deployment and monitor for indicators of compromise that might reveal exploitation attempts. This vulnerability highlights the importance of secure file handling practices and demonstrates how seemingly benign file reference mechanisms can become dangerous attack vectors when proper validation controls are absent, aligning with ATT&CK technique T1059 for command and scripting interpreter and T1203 for Exploitation for Client Execution.