CVE-2009-2270 in DeDeCMS
Summary
by MITRE
Unrestricted file upload vulnerability in member/uploads_edit.php in dedecms 5.3 allows remote attackers to execute arbitrary code by uploading a file with a double extension in the filename, then accessing this file via unspecified vectors, as demonstrated by a .jpg.php filename.
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Analysis
by VulDB Data Team • 11/16/2018
The vulnerability identified as CVE-2009-2270 represents a critical unrestricted file upload flaw within the dedecms content management system version 5.3. This vulnerability exists in the member/uploads_edit.php component and fundamentally compromises the security posture of affected systems by allowing unauthorized users to upload malicious files without proper validation. The flaw specifically manifests when the application fails to adequately sanitize filename inputs, enabling attackers to exploit a double extension technique where files are named with suffixes that bypass typical security checks.
The technical mechanism behind this vulnerability stems from inadequate input validation and file extension checking within the file upload functionality. When an attacker uploads a file with a double extension such as .jpg.php, the system may accept the upload based on the initial extension while failing to properly validate the actual file content or recognize that the file contains executable code within the second extension. This behavior creates a path traversal and code execution vector that can be exploited by remote attackers to gain unauthorized access to the affected system. The vulnerability aligns with CWE-434 which describes insecure file upload conditions where applications accept files without proper validation, and represents a classic example of a path traversal attack pattern.
The operational impact of this vulnerability is severe and multifaceted, potentially allowing attackers to execute arbitrary code on the target system with the privileges of the web application. This capability enables full compromise of the affected server, including data exfiltration, system enumeration, and the installation of persistent backdoors. The attack vector demonstrated through .jpg.php filenames illustrates how attackers can leverage the trust placed in common image file extensions to bypass security controls. Organizations using dedecms 5.3 are particularly at risk as this vulnerability can be exploited without authentication, making it a high-impact threat that can be leveraged for both initial access and privilege escalation within compromised networks.
Security mitigations for CVE-2009-2270 must address both the immediate vulnerability and implement comprehensive file upload validation controls. Organizations should immediately upgrade to a patched version of dedecms that properly validates file extensions and content, implementing strict file type checking that rejects files with multiple extensions or suspicious content. The recommended approach includes validating file content using magic number detection rather than relying solely on filename extensions, implementing proper file upload directories with restricted permissions, and ensuring that uploaded files are not directly executable. Additionally, implementing web application firewalls and security monitoring can help detect and prevent exploitation attempts. This vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Top Ten and aligns with ATT&CK techniques for command and control through web shell deployment and privilege escalation through code execution.