CVE-2017-8507 in Outlook
Summary
by MITRE
A remote code execution vulnerability exists in the way Microsoft Office software parses specially crafted email messages, aka "Microsoft Office Memory Corruption Vulnerability".
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Analysis
by VulDB Data Team • 12/28/2020
The vulnerability identified as CVE-2017-8507 represents a critical remote code execution flaw within Microsoft Office software that specifically targets the parsing mechanisms used when processing email messages. This vulnerability stems from improper handling of specially crafted email content that can trigger memory corruption issues during the rendering process. The flaw affects multiple Microsoft Office applications including Word, Excel, and PowerPoint when they encounter maliciously constructed email attachments or embedded content. Security researchers have classified this as a memory corruption vulnerability that can be exploited through social engineering tactics where users open malicious email attachments or view crafted email content within Office applications. The vulnerability is particularly concerning because it can be triggered remotely through email messages without requiring user interaction beyond opening the malicious content, making it a prime target for phishing campaigns and targeted attacks.
The technical root cause of this vulnerability lies in how Microsoft Office applications handle memory allocation and deallocation when processing certain types of email content. When Office parses email messages containing crafted malicious data structures, the application fails to properly validate input parameters before processing them, leading to buffer overflows or memory corruption conditions. This memory corruption can be leveraged by attackers to execute arbitrary code within the context of the user's privileges. The vulnerability specifically manifests when Office applications attempt to render embedded objects or complex formatting elements within email messages, particularly those that contain malformed or oversized data structures. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read and CWE-787: Out-of-bounds Write, both of which are common indicators of memory corruption issues that can lead to remote code execution. The attack vector follows the ATT&CK framework's technique T1193: Spearphishing Attachment, where attackers deliver malicious Office documents through email to compromise target systems.
The operational impact of CVE-2017-8507 extends far beyond simple exploitation as it provides attackers with persistent access to compromised systems through the execution of arbitrary code. Once successfully exploited, attackers can establish backdoors, escalate privileges, and maintain long-term access to affected networks. The vulnerability affects organizations across all sectors since email remains one of the primary attack vectors for cyber threats, making it particularly dangerous for enterprises with large user bases. Organizations running affected versions of Microsoft Office are at risk of data breaches, system compromise, and potential lateral movement within their networks. The vulnerability can be exploited through various email delivery methods including spam campaigns, targeted spearphishing attacks, and zero-day exploits that leverage the element of surprise. The remote execution capability means that attackers do not need physical access to systems or network proximity to exploit the vulnerability, making it particularly dangerous for organizations with distributed workforces or remote access capabilities.
Mitigation strategies for CVE-2017-8507 require immediate action from organizations to protect their systems from exploitation. Microsoft released security patches and updates that address the vulnerability, and organizations must deploy these patches as soon as possible to prevent exploitation attempts. The recommended approach includes implementing email filtering solutions that can detect and block malicious attachments before they reach end users, particularly those with Office document formats. Network segmentation and application whitelisting can help reduce the attack surface by limiting which applications can execute on systems. Security teams should also implement monitoring solutions that can detect suspicious Office application behavior or memory access patterns that might indicate exploitation attempts. Organizations should conduct regular security awareness training to educate users about the dangers of opening suspicious email attachments and verify the legitimacy of email content before interacting with potentially malicious files. The implementation of the principle of least privilege ensures that even if exploitation occurs, the attacker's capabilities are limited by the permissions of the compromised account. Additionally, organizations should maintain up-to-date backup solutions and incident response procedures to quickly recover from successful exploitation attempts and prevent data loss or further compromise of their systems.