CVE-2006-4581 in The Address Book
Summary
by MITRE
Unrestricted file upload vulnerability in The Address Book 1.04e validates the Content-Type header but not the file extension, which allows remote attackers to upload arbitrary PHP scripts.
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Analysis
by VulDB Data Team • 10/01/2017
The vulnerability described in CVE-2006-4581 represents a critical security flaw in The Address Book version 1.04e application that demonstrates poor input validation practices and inadequate file upload sanitization mechanisms. This issue arises from the application's failure to properly validate file extensions during the upload process, creating a pathway for malicious actors to bypass security controls that are otherwise in place to validate content type headers. The vulnerability specifically affects web applications that rely on Content-Type header validation as their primary security measure while neglecting to implement proper file extension filtering or content verification. This oversight creates a dangerous gap in the application's security posture that can be exploited to gain unauthorized access to the underlying system.
The technical implementation of this vulnerability stems from the application's reliance on Content-Type header validation as the sole mechanism for determining file type legitimacy. When a user uploads a file, the system checks the Content-Type header sent by the client to verify that the file matches expected parameters such as image/jpeg or application/pdf. However, this validation process fails to examine the actual file extension or perform deeper content analysis to confirm that the uploaded file matches its declared type. Attackers can exploit this by uploading a file with a legitimate content type header such as image/jpeg while using a malicious file extension like .php or .phtml, thereby bypassing the security controls. This flaw directly relates to CWE-434 which describes the weakness of unrestricted upload of executable files, and represents a classic example of insufficient input validation in web applications. The vulnerability also aligns with ATT&CK technique T1505.003 which focuses on server-side include attacks, as the ability to upload PHP scripts creates opportunities for server-side code execution.
The operational impact of this vulnerability is severe and far-reaching, as it allows remote attackers to execute arbitrary code on the target system with the privileges of the web server. Once an attacker successfully uploads a malicious PHP script, they can leverage this access to perform various malicious activities including data exfiltration, privilege escalation, system enumeration, and establishing persistent access through backdoor creation. The vulnerability can be exploited through simple web browser interactions without requiring special tools or extensive technical knowledge, making it particularly dangerous for widespread exploitation. Organizations using The Address Book 1.04e are at risk of complete system compromise, data breaches, and potential lateral movement within their network infrastructure. The impact extends beyond immediate system compromise to include regulatory compliance violations, financial losses, and reputational damage that can result from successful exploitation of this vulnerability.
Effective mitigation strategies for CVE-2006-4581 require implementing comprehensive file upload validation mechanisms that go beyond simple Content-Type header checks. Organizations should implement strict file extension filtering that maintains allowlists of permitted file types and rejects any uploads that do not match these approved extensions. Additionally, the application should perform thorough content analysis to verify that the file's actual content matches its declared type, using techniques such as file signature validation or MIME type detection. Implementing proper file storage practices including storing uploaded files outside the web root directory and using randomized filenames can significantly reduce the risk of successful exploitation. Organizations should also consider implementing multiple layers of validation including server-side checks, client-side restrictions, and proper access controls for uploaded files. These measures align with security best practices outlined in OWASP Top Ten and provide defense-in-depth protection against similar vulnerabilities. The implementation of these mitigations should be complemented by regular security assessments and vulnerability scanning to ensure ongoing protection against evolving threat landscapes.