CVE-2020-21862 in DuxCMS
Summary
by MITRE • 07/06/2023
Directory traversal vulnerability in DuxCMS 2.1 allows attackers to delete arbitrary files via /admin/AdminBackup/del.
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Analysis
by VulDB Data Team • 07/24/2023
The vulnerability identified as CVE-2020-21862 represents a critical directory traversal flaw within DuxCMS 2.1 content management system. This weakness specifically manifests in the administrative backup module at the /admin/AdminBackup/del endpoint, where insufficient input validation allows malicious actors to manipulate file paths and execute unauthorized deletion operations. The vulnerability stems from improper sanitization of user-supplied parameters that are directly incorporated into file system operations without adequate security checks or path normalization. Attackers can exploit this flaw by crafting malicious requests that include directory traversal sequences such as ../ or ..\ to navigate outside the intended directory structure and target arbitrary files on the server filesystem.
From a technical perspective this vulnerability maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw operates by bypassing normal access controls and file system boundaries through the manipulation of file path parameters. When the application processes the delete request, it fails to validate or sanitize the input that determines which backup files to remove, allowing an attacker to specify any file path within the server's file system. This represents a classic case of insufficient input validation combined with inadequate access control mechanisms, creating a pathway for arbitrary file deletion that can result in complete system compromise.
The operational impact of this vulnerability extends far beyond simple data loss, as it provides attackers with the capability to remove critical system files, configuration data, or application binaries that could lead to complete system outages or further exploitation. An attacker who successfully exploits this vulnerability could delete essential backup files, corrupt the CMS installation, or remove security-related components that would facilitate additional attacks. The administrative context of the vulnerability means that successful exploitation requires authentication to the administrative interface, but once achieved, the impact is severe as it allows for complete compromise of the content management system's integrity. This vulnerability particularly affects organizations that rely on DuxCMS 2.1 for their web presence and could result in service disruption, data loss, and potential regulatory compliance violations.
Mitigation strategies for CVE-2020-21862 should focus on implementing proper input validation and sanitization at the application level, specifically within the administrative backup module. Organizations should immediately apply the vendor-provided security patches or upgrade to a patched version of DuxCMS that addresses this vulnerability. Access control measures must be strengthened through proper authentication mechanisms, role-based access controls, and limiting administrative privileges to only necessary personnel. Additionally, implementing web application firewalls with path traversal detection capabilities, conducting regular security code reviews, and establishing proper file system permissions can help prevent exploitation of similar vulnerabilities. The remediation process should also include thorough testing of the patched application to ensure that the fix does not introduce any regressions or unintended side effects that could impact legitimate administrative operations. Organizations should consider implementing security monitoring and incident response procedures to detect and respond to potential exploitation attempts.
The vulnerability aligns with several ATT&CK techniques including T1059.001 for command and scripting interpreter, T1566.001 for credential access, and T1486 for data destruction, as it provides an attack path that can lead to complete system compromise and data loss. The attack surface is particularly concerning in environments where administrative access is not properly restricted or monitored, as it can be leveraged as a stepping stone for more sophisticated attacks. Security professionals should also consider this vulnerability in the context of broader security frameworks such as NIST SP 800-53 controls, specifically focusing on access control and system and information integrity controls that address improper input validation and privilege escalation scenarios.