CVE-2008-7157 in EkinBoard
Summary
by MITRE
Unrestricted file upload vulnerability in EkinBoard 1.1.0 and earlier allows remote attackers to execute arbitrary code by uploading an avatar file with an executable extension followed by a safe extension, then accessing it via a direct request to the file in uploaded/avatars/.
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Analysis
by VulDB Data Team • 10/13/2024
The CVE-2008-7157 vulnerability represents a critical unrestricted file upload flaw in EkinBoard version 1.1.0 and earlier systems. This vulnerability stems from inadequate input validation and sanitization mechanisms within the avatar upload functionality, creating a pathway for remote attackers to bypass security restrictions and execute malicious code. The flaw specifically targets the file extension handling process, where the application fails to properly validate or sanitize the uploaded file names, allowing attackers to manipulate the file extension sequence to circumvent detection mechanisms. The vulnerability is particularly concerning as it enables arbitrary code execution through a seemingly benign avatar upload process that should only accept image files. This weakness directly violates the principle of least privilege and demonstrates a fundamental failure in the application's security architecture.
The technical exploitation of this vulnerability relies on the attacker's ability to manipulate file extensions by appending an executable extension followed by a safe extension in the filename. For instance, an attacker might upload a file named shell.php.jpg, where the .php extension is placed first, followed by the .jpg extension. The application's insufficient validation logic fails to properly parse or reject such file names, allowing the system to treat the file as an image while actually storing it with its executable extension. This creates a scenario where the uploaded file can be executed as code when accessed through the direct URL path /uploaded/avatars/. The vulnerability is classified as a CWE-434 Unrestricted Upload of File with Dangerous Type, which is a well-documented weakness in web application security. This specific implementation flaw aligns with ATT&CK technique T1190 for Exploit Public-Facing Application and T1059.007 for Command and Scripting Interpreter for PHP.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with persistent remote code execution capabilities on the affected server. Once successfully exploited, attackers can establish backdoors, install malware, steal sensitive data, or use the compromised system as a launch point for further attacks within the network. The vulnerability affects the integrity and confidentiality of the entire application ecosystem, as the uploaded files are stored in the public web directory structure, making them accessible to anyone with knowledge of the direct URL path. The implications extend beyond immediate code execution to include potential privilege escalation, data exfiltration, and service disruption. Organizations running affected versions of EkinBoard face significant risk of unauthorized access, data breaches, and potential regulatory compliance violations. The vulnerability's impact is amplified by the fact that it can be exploited without authentication, making it particularly dangerous in environments where the application is publicly accessible.
Mitigation strategies for CVE-2008-7157 must address both the immediate vulnerability and the underlying architectural issues that enabled it. Organizations should immediately upgrade to EkinBoard versions that have patched this vulnerability, as the developers have likely implemented proper file extension validation and sanitization mechanisms. The recommended approach involves implementing strict file type validation that checks the actual file content rather than relying solely on extensions, using a whitelist of allowed file types, and ensuring that uploaded files are stored outside the web root directory. Additionally, the application should implement proper filename sanitization, remove or escape special characters, and enforce strict access controls on uploaded files. Security measures should include the use of Content Security Policy headers, proper file permission settings, and regular security audits of file upload functionalities. Organizations should also consider implementing intrusion detection systems to monitor for suspicious file upload activities and establish incident response procedures for handling potential exploitation attempts. The remediation process should include comprehensive testing to ensure that all file upload mechanisms are properly secured and that the application no longer accepts executable files through the avatar upload feature.