CVE-2013-0095 in Office for Mac 2011
Summary
by MITRE
Outlook in Microsoft Office for Mac 2008 before 12.3.6 and Office for Mac 2011 before 14.3.2 allows remote attackers to trigger access to a remote URL and consequently confirm the rendering of an HTML e-mail message by including unspecified HTML5 elements and leveraging the installation of a WebKit browser on the victim s machine, aka "Unintended Content Loading Vulnerability."
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Analysis
by VulDB Data Team • 12/28/2024
This vulnerability represents a sophisticated cross-site scripting attack vector that exploits the interaction between Microsoft Office for Mac and the WebKit rendering engine. The flaw exists in Outlook for Mac 2008 and 2011 versions prior to their respective security updates, specifically affecting Office 2008 before 12.3.6 and Office 2011 before 14.3.2. The vulnerability stems from how the email client handles HTML content when rendering messages, creating an unintended content loading mechanism that can be exploited by remote attackers.
The technical exploitation occurs through the inclusion of unspecified HTML5 elements within email messages that trigger automatic URL access when the email is rendered. This behavior leverages the WebKit browser component that is installed on the victim's machine as part of the Office suite or system configuration. When an attacker crafts a malicious email containing specific HTML5 elements, the WebKit engine automatically attempts to load resources from remote URLs embedded within the message, bypassing normal security boundaries that should prevent such unauthorized network access from within email clients.
This vulnerability creates significant operational impact as it allows attackers to confirm the successful rendering of HTML email messages without requiring any user interaction beyond opening the email. The attack vector demonstrates the dangerous intersection of web browser capabilities and email client security models, where the presence of WebKit on the system creates an unexpected attack surface. The vulnerability can be exploited to perform reconnaissance activities, confirm successful delivery of phishing campaigns, or establish command and control communication channels that would otherwise be blocked by traditional email security measures.
From a cybersecurity perspective, this vulnerability maps to CWE-1057, which describes weaknesses in web browser implementations that allow unintended content loading, and aligns with ATT&CK technique T1566.001 for spearphishing via email. The flaw represents a classic case of insufficient input validation and improper handling of web content within desktop applications, where the email client's security boundaries are not properly enforced against embedded web content. Organizations using affected Office versions face increased risk of targeted attacks, as attackers can use this vulnerability to validate their phishing campaigns or establish covert communication channels, making it particularly dangerous for enterprise environments where email security is critical.
Mitigation strategies should focus on immediate patch deployment for the affected Office versions, implementing strict email content filtering policies, and disabling automatic URL loading for HTML content within email clients. Network-level protections such as web application firewalls and DNS filtering can provide additional defense in depth. Security teams should also consider implementing email sandboxing techniques and monitoring for unusual network connections originating from email clients, as the vulnerability creates a persistent attack surface that can be exploited repeatedly against targeted users.