CVE-2017-8545 in Outlook
Summary
by MITRE
A spoofing vulnerability exists in when Microsoft Outlook for Mac does not sanitize html properly, aka "Microsoft Outlook for Mac Spoofing Vulnerability".
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Analysis
by VulDB Data Team • 09/13/2024
The CVE-2017-8545 vulnerability represents a critical spoofing flaw in Microsoft Outlook for Mac that stems from inadequate HTML sanitization mechanisms within the email client. This vulnerability specifically affects versions of Microsoft Outlook for Mac released prior to the patch released in June 2017, creating a significant security risk for users who rely on the application for email communication. The flaw allows malicious actors to craft specially formatted emails that can deceive users into believing they are viewing legitimate content while actually displaying misleading or harmful information. This type of vulnerability falls under the broader category of cross-site scripting attacks and represents a classic example of insufficient input validation and output sanitization in client-side applications.
The technical implementation of this vulnerability exploits the way Outlook for Mac processes HTML content within email messages. When the application receives emails containing maliciously crafted HTML elements, it fails to properly sanitize or escape these elements before rendering them to the user interface. This allows attackers to inject HTML tags that can manipulate the visual presentation of emails, potentially causing users to see false information or be misled about the actual source or content of messages. The vulnerability specifically targets the rendering engine's handling of HTML attributes and tags, enabling attackers to create deceptive user interfaces that appear to be legitimate Outlook notifications or corporate communications. According to CWE classification, this represents a CWE-79: Cross-site Scripting vulnerability, where the application fails to properly validate and sanitize user-supplied data before rendering it to end users.
The operational impact of CVE-2017-8545 extends beyond simple visual deception to potentially enable more sophisticated attack vectors including phishing attempts, social engineering campaigns, and credential theft operations. Attackers can leverage this vulnerability to create convincing fake login prompts, fraudulent notifications about email delivery failures, or misleading corporate communications that appear to originate from trusted sources within an organization. This spoofing capability directly aligns with techniques documented in the MITRE ATT&CK framework under the T1566: Phishing tactic, where adversaries use deceptive emails to gain initial access to systems. The vulnerability's exploitation can lead to unauthorized access to sensitive corporate data, compromise of user credentials, and potential lateral movement within network environments where Outlook for Mac is used extensively.
Organizations affected by this vulnerability should immediately implement the Microsoft security patch released in June 2017, which addresses the HTML sanitization flaws in the Outlook for Mac application. System administrators should also consider implementing additional email security measures including advanced threat protection solutions, email filtering systems, and user education programs focused on recognizing spoofed communications. Network monitoring should be enhanced to detect unusual email traffic patterns that might indicate exploitation attempts, while security teams should review email content filtering policies to ensure proper handling of potentially malicious HTML content. The vulnerability demonstrates the critical importance of maintaining up-to-date client applications and highlights the need for comprehensive security testing of email rendering engines. Organizations should also consider implementing multi-factor authentication and zero-trust network access controls to mitigate potential damage from successful spoofing attacks, as the vulnerability could be exploited to gain unauthorized access to sensitive systems through credential theft or social engineering campaigns.