CVE-2019-9752 in Open Ticket Request System
Summary
by MITRE
An issue was discovered in Open Ticket Request System (OTRS) 5.x before 5.0.34, 6.x before 6.0.16, and 7.x before 7.0.4. An attacker who is logged into OTRS as an agent or a customer user may upload a carefully crafted resource in order to cause execution of JavaScript in the context of OTRS. This is related to Content-type mishandling in Kernel/Modules/PictureUpload.pm.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2019-9752 affects the Open Ticket Request System (OTRS) version 5.x prior to 5.0.34, 6.x prior to 6.0.16, and 7.x prior to 7.0.4, representing a critical security flaw that enables unauthorized code execution through crafted resource uploads. This vulnerability specifically resides within the Kernel/Modules/PictureUpload.pm module, which handles file upload functionality within the system. The flaw stems from improper Content-type validation and handling mechanisms that fail to adequately sanitize or verify the nature of uploaded files, creating an avenue for malicious actors to exploit the system's file processing capabilities.
The technical implementation of this vulnerability involves an attacker who has already established authentication as either an agent or customer user within the OTRS system, leveraging their legitimate access privileges to upload malicious resources. The core issue lies in the Content-type mishandling within the PictureUpload.pm module where the system fails to properly validate the actual content of uploaded files against their declared content types. This allows attackers to upload files with JavaScript code embedded within seemingly benign image formats or other media types, bypassing normal security checks that would otherwise prevent execution of malicious scripts. The vulnerability is classified under CWE-434, which specifically addresses Unrestricted Upload of File with Dangerous Type, and represents a significant deviation from secure file handling practices.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary JavaScript code within the context of the OTRS application. This cross-site scripting (XSS) vector can be leveraged to perform various malicious activities including session hijacking, data exfiltration, and further exploitation of the system. The attacker can craft malicious uploads that appear legitimate but contain embedded scripts that execute when the file is processed or viewed within the OTRS environment. This creates a persistent threat vector where malicious code can be executed repeatedly, potentially compromising user sessions and accessing sensitive customer data, support tickets, and internal communications managed through the OTRS platform. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, demonstrating how file upload vulnerabilities can be exploited to execute malicious scripts in web applications.
Mitigation strategies for CVE-2019-9752 require immediate patching of affected OTRS versions to their respective secure releases, with administrators prioritizing updates to versions 5.0.34, 6.0.16, and 7.0.4 or later. Beyond patching, organizations should implement comprehensive file validation mechanisms including strict content-type checking, file extension filtering, and mandatory file signature verification. Security configurations should enforce proper file upload restrictions such as disabling script execution in upload directories, implementing Content Security Policy headers, and establishing robust input sanitization processes. Additionally, network monitoring should be enhanced to detect suspicious upload activities and anomalous file processing patterns, while regular security audits should verify that file handling modules maintain proper validation controls. The vulnerability underscores the importance of defense-in-depth strategies and proper secure coding practices in web application development, particularly when handling user-uploaded content and validating file types through multiple verification layers rather than relying on single validation points.