CVE-2019-13397 in osTicket
Summary
by MITRE
Unauthenticated Stored XSS in osTicket 1.10.1 allows a remote attacker to gain admin privileges by injecting arbitrary web script or HTML via arbitrary file extension while creating a support ticket.
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Analysis
by VulDB Data Team • 10/18/2023
The vulnerability CVE-2019-13397 represents a critical security flaw in osTicket version 1.10.1 that enables unauthenticated stored cross-site scripting attacks. This vulnerability specifically targets the file upload functionality within the support ticket creation process, allowing remote attackers to inject malicious web scripts or HTML code that persists in the system. The flaw occurs when the application fails to properly validate and sanitize file extensions during the ticket creation workflow, creating a persistent XSS vector that can be exploited by unauthorized users.
The technical implementation of this vulnerability stems from insufficient input validation mechanisms within the file handling subsystem of osTicket. When users create support tickets with attachments, the system does not adequately filter or sanitize the file extensions provided by attackers. This weakness enables attackers to upload files with malicious extensions or payloads that execute in the context of authenticated admin sessions. The stored nature of this vulnerability means that once the malicious payload is injected, it remains persistent in the system and executes whenever administrators view the affected tickets or attachments, making it particularly dangerous for maintaining long-term access.
The operational impact of CVE-2019-13397 is severe as it directly enables privilege escalation from unauthenticated to administrative access without requiring any prior credentials or session information. Attackers can craft malicious files with extensions that bypass validation checks, upload them through the support ticket system, and then wait for administrators to view the tickets containing these files. This creates a persistent backdoor mechanism that allows attackers to execute arbitrary commands, steal session cookies, access sensitive customer data, and potentially escalate privileges further within the compromised environment. The vulnerability also undermines the integrity of the support ticket system and can lead to complete system compromise.
Security professionals should implement multiple layers of mitigation for this vulnerability. Immediate patching of osTicket to versions that address this specific XSS flaw is essential, as the vulnerability has been identified and remediated in subsequent releases. Network segmentation and access controls should be implemented to limit administrative access to the support ticket system, while web application firewalls can be configured to detect and block suspicious file upload patterns. Input validation should be strengthened to enforce strict file extension whitelisting and proper sanitization of all user-supplied data. Organizations should also conduct regular security assessments of their help desk systems and implement monitoring for unusual file upload activities that may indicate exploitation attempts. This vulnerability aligns with CWE-79 (Cross-site Scripting) and represents a significant concern under the ATT&CK framework category of privilege escalation through web application vulnerabilities.
The persistence of this vulnerability in the system means that even after initial exploitation, attackers can maintain access through the stored XSS payload that executes in the context of administrator sessions. This characteristic makes the vulnerability particularly dangerous as it can be leveraged for extended periods without detection, potentially leading to data breaches, credential theft, and further compromise of the underlying infrastructure. The vulnerability also highlights the importance of proper input validation and the potential for seemingly benign functionality to become a critical security risk when insufficient sanitization is implemented. Organizations should ensure that all user-supplied content is properly validated and sanitized before being processed or stored within the system to prevent similar vulnerabilities from being exploited in the future.