CVE-2017-8571 in Outlook
Summary
by MITRE
Microsoft Outlook 2007 SP3, Outlook 2010 SP2, Outlook 2013 SP1, Outlook 2013 RT SP1, and Outlook 2016 as packaged in Microsoft Office allows a security feature bypass vulnerability due to the way that it handles input, aka "Microsoft Office Outlook Security Feature Bypass Vulnerability".
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Analysis
by VulDB Data Team • 01/06/2021
The CVE-2017-8571 vulnerability represents a significant security flaw in Microsoft Outlook versions spanning multiple product lines including Outlook 2007 SP3, Outlook 2010 SP2, Outlook 2013 SP1, Outlook 2013 RT SP1, and Outlook 2016. This vulnerability specifically targets the security feature bypass mechanism within the Outlook application, creating a critical weakness that could be exploited by malicious actors to circumvent intended protection measures. The flaw manifests in how Outlook processes and validates input data, particularly when handling specific file formats and email content that trigger the security bypass condition. This vulnerability falls under the broader category of input validation issues that have been classified as CWE-20, which represents "Improper Input Validation" in the Common Weakness Enumeration framework. The security feature bypass occurs when Outlook improperly handles certain input parameters, allowing attackers to potentially execute malicious code or gain unauthorized access to user data without proper authentication or authorization.
The technical exploitation of this vulnerability leverages the way Outlook processes email attachments and embedded content, particularly when dealing with specially crafted files that trigger the security bypass mechanism. Attackers can craft malicious email messages or attachments that, when opened in vulnerable Outlook versions, bypass the application's built-in security protections designed to prevent execution of potentially harmful code. This type of attack aligns with the ATT&CK framework's technique T1204.002, which describes "User Execution: Malicious File," where adversaries rely on users to execute malicious files or attachments. The vulnerability is particularly concerning because it affects multiple versions of Microsoft Outlook, creating a wide attack surface across different organizational environments. The flaw essentially allows threat actors to bypass Outlook's security controls that are meant to prevent the automatic execution of macros, embedded scripts, or other potentially dangerous content, thereby enabling more sophisticated attack vectors.
The operational impact of CVE-2017-8571 extends beyond simple data theft or system compromise, as it can enable more complex attack chains within enterprise environments. Organizations running affected Outlook versions face potential exposure to phishing campaigns, social engineering attacks, and targeted malware delivery that could result in significant data breaches, financial loss, and operational disruption. The vulnerability's persistence across multiple Outlook versions means that organizations cannot simply upgrade a single application to resolve the issue, requiring comprehensive patch management across their entire Microsoft Office suite. Security teams must also consider the broader implications for email security policies and user training programs, as this vulnerability demonstrates the critical importance of maintaining current security patches and implementing layered defense strategies. The vulnerability can be particularly dangerous in environments where users have elevated privileges or access to sensitive corporate data, as successful exploitation could lead to privilege escalation and lateral movement within networks. Organizations should also note that this vulnerability may be exploited in conjunction with other attack techniques, such as initial access through spear-phishing emails or credential theft, making it a particularly dangerous component in comprehensive attack frameworks.
Mitigation strategies for CVE-2017-8571 should include immediate deployment of Microsoft security patches and updates, as well as implementation of additional defensive measures. Organizations should consider disabling macro execution in Outlook unless absolutely necessary, implementing strict email filtering and content scanning mechanisms, and conducting regular security awareness training for users to recognize potential phishing attempts. Network segmentation and monitoring solutions should be employed to detect anomalous email traffic patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining current security patches across all Microsoft Office applications, as similar vulnerabilities often exist in related components. Security teams should also implement monitoring for suspicious file execution patterns and establish incident response procedures specifically addressing email-based attack vectors. Regular vulnerability assessments and penetration testing should include evaluation of email client security configurations to identify potential bypass opportunities and ensure that all security controls are properly configured and functioning as intended.