CVE-2006-6786 in Open Newsletter
Summary
by MITRE
Open Newsletter 2.5 and earlier allows remote authenticated administrators to execute arbitrary PHP code by inserting the code into the email parameter to (1) subscribe.php or (2) unsubscribe.php.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability described in CVE-2006-6786 represents a critical remote code execution flaw within the Open Newsletter 2.5 software suite. This issue affects authenticated administrators who possess the ability to manipulate specific parameters within the newsletter subscription system. The vulnerability stems from inadequate input validation and sanitization mechanisms within the email parameter handling functionality of two key files: subscribe.php and unsubscribe.php. The flaw allows an authenticated attacker with administrative privileges to inject malicious PHP code directly into the email parameter, which then gets executed within the context of the web server. This represents a classic command injection vulnerability that can be exploited to gain full control over the affected system. The vulnerability falls under the CWE-94 category of "Improper Control of Generation of Code" and specifically aligns with CWE-74 which addresses "Improper Neutralization of Special Elements in Output Used by a Downstream Component." The attack vector requires an authenticated administrator account, which significantly reduces the attack surface but does not eliminate the severity of the exploit.
The technical implementation of this vulnerability occurs through the improper handling of user-supplied input within the newsletter management system. When an administrator accesses either subscribe.php or unsubscribe.php with a specially crafted email parameter containing PHP code, the system fails to properly sanitize or validate the input before processing it. This lack of proper input filtering allows the malicious code to be executed as part of the normal processing flow, effectively creating a backdoor for code execution. The vulnerability demonstrates poor security practices in parameter handling and input validation that have been well-documented in security frameworks. The attack chain involves an authenticated administrator performing legitimate administrative actions while unknowingly introducing malicious code into the system. This exploitation pattern aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1505.003 for "Server Software Component: Web Shell," though the specific implementation uses PHP rather than PowerShell. The vulnerability essentially transforms legitimate administrative functionality into a code execution vector.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete system compromise capabilities. An authenticated administrator who is compromised or coerced can execute arbitrary code, potentially leading to data theft, system infiltration, or complete server takeover. The vulnerability's impact extends beyond immediate code execution to include potential privilege escalation, lateral movement within the network, and persistent backdoor establishment. Organizations using Open Newsletter 2.5 or earlier versions face significant risk of unauthorized access and potential data breaches. The vulnerability can be exploited to install web shells, modify system files, access sensitive data, or redirect traffic to malicious destinations. Given that the exploitation requires only administrative privileges, the impact is magnified as it can be leveraged by insider threats or compromised accounts. This vulnerability essentially removes the security boundary that administrative privileges should provide, turning legitimate administrative access into a potential attack vector.
Mitigation strategies for CVE-2006-6786 should focus on immediate software updates and comprehensive input validation measures. The most effective immediate solution is upgrading to Open Newsletter version 2.6 or later, which addresses the input validation issues that enable this vulnerability. Organizations should implement strict input validation for all parameters, particularly those used in subscription and unsubscription processes. The implementation of proper sanitization functions and output encoding can prevent malicious code injection. Security measures should include regular vulnerability assessments and penetration testing to identify similar input validation flaws. Network segmentation and access control measures can limit the potential impact if an account is compromised. The vulnerability highlights the importance of the principle of least privilege and proper input validation as outlined in security frameworks such as the OWASP Top Ten. Organizations should also implement application firewalls and web application security monitoring to detect and prevent exploitation attempts. Regular security training for administrators about the risks of code injection attacks and the importance of secure coding practices is essential for preventing such vulnerabilities from being exploited in production environments.