CVE-2017-15280 in Umbraco
Summary
by MITRE
XML external entity (XXE) vulnerability in Umbraco CMS before 7.7.3 allows attackers to obtain sensitive information by reading files on the server or sending TCP requests to intranet hosts (aka SSRF), related to Umbraco.Web/umbraco.presentation/umbraco/dialogs/importDocumenttype.aspx.cs.
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Analysis
by VulDB Data Team • 01/03/2023
The CVE-2017-15280 vulnerability represents a critical XML external entity processing flaw discovered in Umbraco CMS versions prior to 7.7.3. This vulnerability specifically affects the importDocumenttype.aspx.cs page within the Umbraco.Web/umbraco.presentation/umbraco/dialogs/ directory structure, making it a targeted attack vector within the content management system's administrative interface. The flaw stems from insufficient input validation and sanitization of XML data processing, creating a pathway for malicious actors to exploit the system's XML parser configuration. This vulnerability is classified under CWE-611 as an Improper Restriction of XML External Entity Reference, which directly relates to the insecure handling of external entity references in XML processing components. The attack surface is particularly concerning as it targets the administrative import functionality, which typically operates with elevated privileges and system-level access rights within the CMS environment.
The technical exploitation of this XXE vulnerability enables attackers to perform two primary malicious activities that demonstrate the severity of the flaw. First, the vulnerability allows for arbitrary file reading on the server, potentially exposing sensitive system files, configuration data, database credentials, or other confidential information stored within the application's file system. This capability directly violates the principle of least privilege and can lead to complete system compromise when sensitive files containing authentication tokens, database connection strings, or application secrets are accessed. Second, the vulnerability facilitates server-side request forgery attacks by enabling attackers to send TCP requests to internal network hosts that would normally be protected by firewalls or network segmentation. This SSRF capability allows threat actors to probe internal network services, potentially mapping network topology, accessing internal APIs, or even exploiting other vulnerable services within the internal network that are not directly exposed to the internet. The combination of these attack vectors makes this vulnerability particularly dangerous as it can serve as a stepping stone for further network infiltration and lateral movement within compromised environments.
The operational impact of this vulnerability extends beyond immediate data theft and system compromise, creating long-term security implications for organizations using affected Umbraco installations. Attackers leveraging this vulnerability can systematically enumerate system resources, identify internal services, and potentially establish persistent access points within the network infrastructure. The vulnerability's presence in the administrative import functionality means that even limited user access could potentially be escalated to full system compromise if the import feature is accessible to unauthorized users or if the system lacks proper access controls. Organizations may face significant regulatory and compliance violations if sensitive data is accessed or exfiltrated through this vector, particularly in environments governed by standards such as pci dss, hipaa, or gdpr. The vulnerability also demonstrates poor security practices in XML processing, highlighting the importance of implementing proper input validation, disabling external entity resolution, and maintaining up-to-date security configurations for all web applications. This flaw aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments and T1071.004 for application layer protocol usage, particularly in the context of XML-based attacks and server-side request forgery operations.
The recommended mitigations for this vulnerability focus on immediate remediation and long-term security hardening measures. Organizations must upgrade to Umbraco CMS version 7.7.3 or later, which contains the necessary patches to address the XXE vulnerability in the importDocumenttype functionality. Additionally, implementing proper XML parser configuration settings to disable external entity resolution and DTD processing prevents similar vulnerabilities from manifesting in other components. Network segmentation and access controls should be enforced to limit access to administrative functions, ensuring that only authorized personnel can utilize import features. Input validation and sanitization measures should be strengthened across all XML processing components, with particular attention to the umbraco presentation layer where this vulnerability was identified. Security monitoring should include detection of unusual file access patterns and outbound network requests that could indicate exploitation attempts. The implementation of web application firewalls and security scanning tools can help identify and block malicious XML payloads before they reach the vulnerable components. Organizations should also conduct comprehensive security assessments of their web applications to identify other potential XXE vulnerabilities in XML processing functionality, as this vulnerability represents a broader class of issues that require systematic addressing across the entire application stack. Regular security updates and patch management processes should be implemented to prevent similar vulnerabilities from being introduced through third-party components or custom application code that may also process XML data without proper security controls.