CVE-2016-5124 in Open-Xchange
Summary
by MITRE
An issue was discovered in Open-Xchange OX App Suite before 7.8.1-rev14. Adding images from external sources to HTML editors by drag&drop can potentially lead to script code execution in the context of the active user. To exploit this, a user needs to be tricked to use an image from a specially crafted website and add it to HTML editor areas of OX App Suite, for example E-Mail Compose or OX Text. This specific attack circumvents typical XSS filters and detection mechanisms since the code is not loaded from an external service but injected locally. Malicious script code can be executed within a user's context. This can lead to session hijacking or triggering unwanted actions via the web interface (sending mail, deleting data etc.). To exploit this vulnerability, a attacker needs to convince a user to follow specific steps (social-engineering).
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Analysis
by VulDB Data Team • 06/26/2024
The vulnerability identified as CVE-2016-5124 represents a critical security flaw in Open-Xchange OX App Suite versions prior to 7.8.1-rev14, specifically targeting the HTML editor component's handling of drag-and-drop image operations. This issue stems from insufficient input validation and sanitization mechanisms within the application's rich text editing functionality, creating a pathway for malicious code execution that operates within the context of authenticated users. The vulnerability is particularly concerning because it leverages a sophisticated attack vector that bypasses traditional cross-site scripting detection mechanisms, making it more difficult to identify and prevent through conventional security measures.
The technical exploitation of this vulnerability occurs through a carefully crafted social engineering campaign where attackers manipulate users into performing specific actions that trigger the malicious code execution. When users drag and drop images from specially constructed websites into HTML editor areas such as email composition fields or OX Text components, the application fails to properly sanitize the image metadata or source attributes. This flaw allows attackers to inject executable script code directly into the HTML content, which then executes when the user interacts with the compromised content. The attack circumvents typical XSS filters because the malicious code is embedded within the image itself rather than being delivered through external script sources, making it particularly stealthy and difficult to detect through standard network monitoring or web application firewall rules.
The operational impact of this vulnerability extends beyond simple code execution, creating significant risks for user sessions and data integrity within the OX App Suite environment. Successful exploitation can lead to complete session hijacking where attackers gain unauthorized access to user accounts and can perform actions as if they were legitimate users. This includes sending unauthorized emails, deleting critical data, modifying user permissions, or accessing sensitive information stored within the application. The vulnerability affects core collaboration features such as email composition and document editing, making it particularly dangerous in enterprise environments where users frequently engage with rich text editors. The local injection nature of the attack means that the malicious code operates within the same security context as legitimate user operations, making it extremely difficult to distinguish between benign and malicious content at runtime.
Security professionals should recognize this vulnerability as a variant of CWE-79 Cross-site Scripting and aligns with ATT&CK technique T1203 Exploitation for Client Execution, specifically targeting user-facing applications with rich text capabilities. Organizations should implement immediate mitigations including updating to OX App Suite version 7.8.1-rev14 or later, implementing stricter content validation policies for drag-and-drop operations, and deploying enhanced monitoring for suspicious image handling activities. Additional protective measures include user education regarding social engineering risks, network segmentation to limit potential attack surfaces, and implementation of web application firewalls with advanced content inspection capabilities. The vulnerability demonstrates the critical importance of validating all user-supplied content, particularly in rich text editing environments where multiple input vectors can be exploited simultaneously, and underscores the need for comprehensive security testing of user interaction components in enterprise collaboration platforms.