CVE-2020-18705 in Quokka
Summary
by MITRE • 08/16/2021
XML External Entities (XXE) in Quokka v0.4.0 allows remote attackers to execute arbitrary code via the component 'quokka/core/content/views.py'.
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Analysis
by VulDB Data Team • 08/19/2021
The vulnerability identified as CVE-2020-18705 represents a critical XML External Entities (XXE) flaw discovered in Quokka v0.4.0, a content management system designed for web applications. This vulnerability resides within the component 'quokka/core/content/views.py' and exposes the application to remote code execution attacks. The XXE vulnerability occurs when an application processes XML input without proper validation or sanitization, allowing attackers to manipulate XML parsers and potentially access local system resources or execute arbitrary commands on the affected server. This type of vulnerability falls under CWE-611, which specifically addresses XML External Entity Processing vulnerabilities, and aligns with ATT&CK technique T1213.002 for data from information repositories. The flaw is particularly dangerous because it enables attackers to leverage the XML processing capabilities of the application to perform unauthorized operations, potentially leading to full system compromise.
The technical implementation of this vulnerability involves the improper handling of XML data within the content views module of Quokka. When the application processes XML content through the affected endpoint, it fails to properly restrict external entity references, allowing malicious XML payloads to include references to external resources. Attackers can construct specially crafted XML documents that, when processed by the vulnerable application, trigger the XML parser to fetch external resources or execute system commands. This typically occurs through the use of external entity declarations within XML documents, where attackers can reference local files, perform server-side request forgery attacks, or even execute arbitrary code on the target system. The vulnerability specifically affects the content management functionality of the application, making it particularly dangerous for systems that process user-submitted content or external data feeds.
The operational impact of CVE-2020-18705 extends beyond simple data theft or service disruption, as it provides attackers with the capability to achieve complete system compromise. Remote code execution vulnerabilities of this nature allow threat actors to gain persistent access to affected systems, potentially leading to data breaches, system infiltration, and further lateral movement within network environments. The vulnerability affects the core content processing functionality of Quokka, meaning that any user who can submit content or access the affected views could potentially exploit this flaw. Organizations using Quokka v0.4.0 are particularly at risk since the vulnerability enables attackers to bypass traditional security controls and directly execute commands on the application server, potentially leading to unauthorized access to databases, file systems, and other critical resources. This makes the vulnerability particularly attractive to attackers seeking to establish persistent backdoors or escalate privileges within compromised environments.
Mitigation strategies for CVE-2020-18705 should focus on implementing proper XML input validation and sanitization throughout the application. The most effective approach involves disabling external entity resolution in XML parsers and implementing strict input validation for all XML processing components. Organizations should upgrade to Quokka versions that have addressed this vulnerability, as the maintainers have likely implemented proper XML parsing controls and input sanitization measures. Security measures should include configuring XML parsers to reject external entity declarations, implementing proper access controls for content submission, and conducting regular security assessments of XML processing components. Additionally, organizations should deploy web application firewalls that can detect and block XXE attack patterns, implement network segmentation to limit the impact of potential exploitation, and establish monitoring procedures to detect unusual system activity that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of secure coding practices and proper input validation, particularly for applications that process external data or user-submitted content, as these components often represent the most common attack vectors in modern web applications.