CVE-2016-4026 in OX AppSuite
Summary
by MITRE
An issue was discovered in Open-Xchange OX App Suite before 7.8.1-rev11. The content sanitizer component has an issue with filtering malicious content in case invalid HTML code is provided. In such cases the filter will output a unsanitized representation of the content. 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.). Attackers can use this issue for filter evasion to inject script code later on.
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Analysis
by VulDB Data Team • 10/08/2022
The vulnerability identified as CVE-2016-4026 resides within the Open-Xchange OX App Suite email platform, specifically within its content sanitizer component that operates as a critical security control for filtering potentially malicious content. This flaw represents a significant weakness in the application's defense-in-depth strategy, as the sanitizer component is designed to prevent cross-site scripting attacks by removing or neutralizing dangerous HTML and script code. The vulnerability affects versions prior to 7.8.1-rev11, indicating that this was a known issue that required a specific patch release to address the underlying security flaw. The problem manifests when the sanitizer encounters invalid HTML code, which triggers a failure in the filtering mechanism, resulting in unsanitized content being rendered to end users.
The technical nature of this vulnerability stems from improper handling of malformed HTML input within the content sanitization process, creating a condition where the security filter fails to properly validate and sanitize the content. This represents a classic case of inadequate input validation and sanitization, which maps directly to CWE-79 - Improper Neutralization of Input During Web Page Generation. When the sanitizer processes invalid HTML structures, it fails to properly parse or filter the content, allowing malicious script code to persist in the output. The vulnerability essentially creates a bypass mechanism where attackers can exploit the sanitizer's inability to handle malformed input, enabling them to inject and execute arbitrary scripts within the context of authenticated users.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with a pathway to execute malicious code in the context of legitimate users, potentially leading to complete session compromise. Session hijacking becomes a direct consequence, as the injected scripts can capture session tokens, cookies, or other authentication credentials that would normally remain protected. Additionally, the vulnerability enables attackers to perform unauthorized actions through the web interface, including sending emails, deleting data, or modifying user settings, all without the victim's knowledge or consent. This represents a significant escalation from simple information disclosure to full blown privilege escalation and data manipulation capabilities. The attack vector leverages the web application's trust in its own sanitization mechanisms, making it particularly dangerous as it operates within the normal user interaction flow.
The implications of this vulnerability extend beyond immediate exploitation to include broader security implications for the email platform and its users. Attackers can utilize this weakness for filter evasion techniques, allowing them to bypass other security controls and potentially establish persistent access through more sophisticated attack chains. The vulnerability aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: JavaScript, as it enables the execution of malicious JavaScript code within the user context. Organizations using the affected versions of OX App Suite face significant risk of credential theft, data exfiltration, and unauthorized access to sensitive email communications. The remediation strategy requires immediate deployment of the 7.8.1-rev11 patch, which addresses the sanitization logic to properly handle invalid HTML structures. Security teams should also implement additional monitoring for suspicious content patterns and consider implementing web application firewalls as additional protective layers to mitigate potential exploitation attempts.