CVE-2015-8813 in Umbraco
Summary
by MITRE
The Page_Load function in Umbraco.Web/umbraco.presentation/umbraco/dashboard/FeedProxy.aspx.cs in Umbraco before 7.4.0 allows remote attackers to conduct server-side request forgery (SSRF) attacks via the url parameter.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability identified as CVE-2015-8813 represents a critical server-side request forgery flaw in the Umbraco content management system. This vulnerability exists within the Page_Load function of the FeedProxy.aspx.cs file, which is part of the dashboard functionality designed to fetch and display external feed content. The flaw allows remote attackers to manipulate the url parameter and potentially redirect the application's requests to arbitrary destinations, creating a pathway for malicious actors to exploit the system's trust in internal network resources.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the FeedProxy component. When the application processes the url parameter passed to the Page_Load function, it fails to properly validate or restrict the destination of the HTTP requests being made. This oversight enables attackers to specify any URL they choose, potentially bypassing network security controls and accessing internal systems that should remain protected from external access. The vulnerability directly maps to CWE-918, which defines server-side request forgery as a condition where a web application accepts untrusted input that can be used to make HTTP requests to arbitrary destinations.
The operational impact of this vulnerability extends beyond simple data exfiltration, as it can enable attackers to perform reconnaissance activities against internal networks, access sensitive data stored on internal servers, and potentially escalate privileges through information gathering. Attackers could leverage this flaw to probe internal services, discover network topology, access internal APIs, or even attempt to exploit other vulnerabilities within the internal infrastructure that are not directly exposed to the internet. The attack surface is particularly concerning given that Umbraco is a widely used content management system with numerous deployments across various organizations, making this vulnerability a high-value target for threat actors.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to Umbraco version 7.4.0 or later, which contains the necessary patches to address the SSRF vulnerability. Additionally, network-level controls such as firewall rules that restrict outbound connections from the Umbraco application server to internal networks can provide additional defense-in-depth measures. The implementation of proper input validation and the use of allowlists for permitted URLs can further reduce the risk of exploitation. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1071.004 (Application Layer Protocol: DNS) and T1566 (Phishing), as attackers could use the SSRF capability to redirect requests to malicious domains or internal systems, potentially leading to credential theft or further compromise of the affected environment.