CVE-2020-25912 in Symphony
Summary
by MITRE • 10/31/2021
A XML External Entity (XXE) vulnerability was discovered in symphony\lib\toolkit\class.xmlelement.php in Symphony 2.7.10 which can lead to an information disclosure or denial of service (DOS).
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Analysis
by VulDB Data Team • 11/04/2021
The vulnerability identified as CVE-2020-25912 represents a critical XML External Entity processing flaw within the symphony\lib toolkit component. This issue stems from insufficient input validation when processing XML data, allowing malicious actors to exploit the system's handling of external entities. The vulnerability manifests when the toolkit processes XML documents that contain references to external resources, potentially enabling unauthorized access to internal systems or data exfiltration. The flaw exists in the XML parsing mechanism where external entity declarations are not properly sanitized or restricted, creating an attack surface that can be leveraged for various malicious activities including server-side request forgery and denial of service conditions. This vulnerability directly maps to CWE-611, which categorizes insecure XML processing as a significant security weakness in software applications.
The technical implementation of this XXE vulnerability allows attackers to craft specially formatted XML payloads that reference external entities hosted on attacker-controlled servers. When the symphony\lib toolkit processes such malformed XML data, it attempts to resolve these external references, potentially leading to information disclosure, internal network enumeration, or even remote code execution depending on the underlying system configuration. The vulnerability can be exploited through various attack vectors including file inclusion, data exfiltration, and service disruption. Attackers can leverage this weakness to access sensitive internal resources that would normally be protected by network segmentation, as the toolkit's XML parser does not adequately restrict external entity resolution. This type of vulnerability is particularly dangerous in enterprise environments where internal systems may contain sensitive data or critical infrastructure components.
The operational impact of CVE-2020-25912 extends beyond simple data exposure, as it can enable sophisticated attack chains that compromise entire application ecosystems. Organizations utilizing the affected symphony\lib toolkit may experience unauthorized access to internal databases, file systems, or network resources through this XXE vulnerability. The attack surface is particularly concerning given that XML processing is commonly used in web services, data interchange formats, and configuration management systems. This vulnerability aligns with ATT&CK technique T1059.007, which covers XML and script-based execution, and can facilitate lateral movement within networks when combined with other exploitation techniques. The potential for privilege escalation exists if the toolkit operates with elevated system permissions, making this vulnerability particularly dangerous in production environments.
Mitigation strategies for CVE-2020-25912 should focus on implementing robust XML input validation and disabling external entity processing entirely within the symphony\lib toolkit. Organizations should configure XML parsers to reject external entity declarations and ensure that all XML processing occurs within secure sandboxes or restricted environments. The most effective remediation involves updating to the latest version of the toolkit that addresses this XXE vulnerability, as vendors typically provide patches that disable external entity resolution by default. Additionally, implementing network segmentation, firewall rules, and monitoring for suspicious XML processing activities can help detect and prevent exploitation attempts. Security teams should also consider deploying web application firewalls that can identify and block malicious XML payloads attempting to exploit XXE vulnerabilities. Regular security assessments and input validation testing should be conducted to ensure that similar vulnerabilities do not exist in other components of the application stack. The implementation of secure coding practices and adherence to OWASP XML security guidelines should be enforced throughout the development lifecycle to prevent future occurrences of this class of vulnerability.