CVE-2014-8686 in CodeIgniter
Summary
by MITRE
CodeIgniter before 2.2.0 makes it easier for attackers to decode session cookies by leveraging fallback to a custom XOR-based encryption scheme when the Mcrypt extension for PHP is not available.
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Analysis
by VulDB Data Team • 01/10/2025
The vulnerability identified as CVE-2014-8686 affects CodeIgniter versions prior to 2.2.0 and represents a significant security weakness in session management that directly impacts the confidentiality of user data. This flaw arises from the framework's encryption fallback mechanism when the Mcrypt extension is unavailable in the PHP environment. The issue creates a scenario where attackers can more easily decode session cookies through a custom XOR-based encryption scheme that serves as a fallback when the preferred encryption method is not accessible. This vulnerability falls under the category of weak cryptographic implementation and directly relates to CWE-327, which addresses the use of weak or broken cryptographic algorithms. The vulnerability is particularly concerning because it demonstrates a lack of proper fallback security measures when primary encryption methods are unavailable.
The technical implementation of this vulnerability stems from CodeIgniter's session encryption handling logic that automatically switches to a custom XOR encryption method when the Mcrypt extension cannot be loaded. This fallback mechanism, while intended to provide compatibility across different server configurations, creates a dangerous security gap. The XOR-based encryption used in this fallback scenario is fundamentally weak and susceptible to various cryptanalytic attacks including frequency analysis and known-plaintext attacks. When the Mcrypt extension is disabled or unavailable, the framework defaults to this insecure method, making session cookie contents vulnerable to decryption by malicious actors. The operational impact is significant because session cookies typically contain sensitive information including user authentication tokens, session identifiers, and potentially other confidential data that could be exploited for unauthorized access to user accounts.
Attackers can exploit this vulnerability by intercepting session cookies and applying standard cryptanalysis techniques to reverse-engineer the XOR-encrypted data without requiring the encryption key. This type of attack aligns with techniques described in the MITRE ATT&CK framework under the T1552 category for unsecured credentials, specifically targeting credential exposure through weak encryption. The vulnerability essentially provides attackers with a pathway to bypass normal authentication mechanisms and potentially gain unauthorized access to user sessions, making it a critical concern for web applications relying on CodeIgniter frameworks. The ease of exploitation stems from the predictable nature of XOR encryption and the fact that attackers can often determine the encryption key through pattern analysis or by leveraging known session data.
The recommended mitigation strategy involves upgrading to CodeIgniter version 2.2.0 or later, which addresses this vulnerability through improved encryption handling and elimination of the insecure fallback mechanism. Organizations should also ensure that the Mcrypt extension is properly configured and available in their PHP environments to prevent the fallback to weak encryption. Additionally, implementing proper security monitoring and regular vulnerability assessments can help detect potential exploitation attempts. System administrators should consider additional security measures such as implementing secure session management practices, using HTTPS encryption for all session communications, and regularly updating all framework components to address known vulnerabilities. The fix implemented in version 2.2.0 demonstrates the importance of proper cryptographic fallback handling and ensures that security is never compromised due to compatibility considerations.