CVE-2019-13608 in Storefront Server
Summary
by MITRE
Citrix StoreFront Server before 1903, 7.15 LTSR before CU4 (3.12.4000), and 7.6 LTSR before CU8 (3.0.8000) allows XXE attacks.
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Analysis
by VulDB Data Team • 02/05/2025
Citrix StoreFront serves as a critical component in enterprise environments, providing secure access to virtual applications and desktops through its web interface. This vulnerability affects multiple versions of the StoreFront server software, specifically those prior to the mentioned patches including the 1903 release, 7.15 LTSR with CU4, and 7.6 LTSR with CU8. The vulnerability stems from improper input validation within the application's XML processing mechanisms, creating an avenue for XML External Entity attacks that can be exploited by remote attackers.
The technical flaw manifests when the application processes XML data without adequate sanitization of external entity references. An attacker can craft malicious XML payloads that, when processed by the vulnerable StoreFront server, can cause the system to parse external resources or perform unauthorized network requests. This vulnerability falls under the Common Weakness Enumeration category CWE-611, which specifically addresses improper restriction of XML external entities, and aligns with ATT&CK technique T1213.002 for data from information repositories. The flaw allows for potential information disclosure, denial of service, and in some cases, remote code execution depending on the server configuration and the attacker's access level.
The operational impact of this vulnerability extends beyond simple data exposure, as it can enable attackers to perform reconnaissance activities against internal networks by leveraging the server's ability to make outbound connections. Attackers can exploit this weakness to access internal systems that might otherwise be protected by firewalls, potentially leading to lateral movement within the enterprise network. The vulnerability affects organizations that rely on Citrix StoreFront for application delivery, particularly those with less restrictive network policies or insufficient monitoring of XML processing activities. Organizations using older versions without proper patch management can face significant security risks, as the attack surface includes not only the initial compromise but also potential escalation opportunities.
Mitigation strategies should prioritize immediate patching of affected systems to the latest supported versions, ensuring that all cumulative updates are applied. Organizations should implement network segmentation to limit the exposure of StoreFront servers and deploy robust input validation mechanisms that prevent XML external entity processing. Security monitoring should be enhanced to detect anomalous XML processing activities, and access controls should be strictly enforced to limit who can interact with the StoreFront interface. Additionally, implementing web application firewalls and conducting regular security assessments of the StoreFront environment can help detect and prevent exploitation attempts. The vulnerability also underscores the importance of maintaining up-to-date patch management procedures and conducting regular vulnerability assessments to identify and remediate similar weaknesses across the enterprise infrastructure.