CVE-2008-4304 in phpCollab
Summary
by MITRE
general/login.php in phpCollab 2.5 rc3 and earlier allows remote attackers to execute arbitrary commands via shell metacharacters in unspecified input related to the SSL_CLIENT_CERT environment variable. NOTE: in some environments, SSL_CLIENT_CERT always has a base64-encoded string value, which may impose constraints on injection for typical shells.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability identified as CVE-2008-4304 affects phpCollab version 2.5 rc3 and earlier, specifically within the general/login.php component. This represents a critical command injection flaw that enables remote attackers to execute arbitrary system commands through maliciously crafted input. The vulnerability manifests when the application processes the SSL_CLIENT_CERT environment variable, which is typically populated in SSL-enabled environments where client certificates are required for authentication. The flaw occurs due to insufficient input validation and sanitization of this environment variable, allowing attackers to inject shell metacharacters that get interpreted by the underlying operating system. This type of vulnerability falls under CWE-77 which categorizes improper neutralization of special elements used in commands, and specifically aligns with CWE-94 which addresses execution of arbitrary code due to improper input validation. The attack vector is particularly concerning as it operates over remote network connections without requiring authentication, making it accessible to any attacker who can establish an SSL connection to the vulnerable system.
The technical exploitation of this vulnerability relies on the application's failure to properly sanitize the SSL_CLIENT_CERT environment variable before processing it within shell command contexts. When phpCollab processes this variable, it likely incorporates it into system calls or shell executions without adequate escaping or filtering of special characters. The SSL_CLIENT_CERT environment variable typically contains base64-encoded certificate data in many server configurations, but this encoding does not prevent command injection attacks when the data flows into shell contexts. Attackers can craft malicious certificate data that includes shell metacharacters such as semicolons, pipes, or backticks that get executed by the system shell when the application processes the input. This vulnerability demonstrates poor input validation practices and highlights the dangers of directly incorporating environment variables into system commands without proper sanitization. The impact extends beyond simple command execution to potentially allow full system compromise, data exfiltration, and persistence mechanisms.
The operational impact of CVE-2008-4304 is severe and multifaceted, affecting organizations that deploy phpCollab in SSL-enabled environments where client certificate authentication is configured. Successful exploitation could result in complete system compromise, allowing attackers to execute arbitrary commands with the privileges of the web server process. This could lead to data breaches, system infiltration, and potential lateral movement within network environments. The vulnerability's remote nature means that attackers do not require physical access or local credentials to exploit it, making it particularly dangerous in publicly accessible applications. Organizations using phpCollab in production environments face significant risk of unauthorized access and potential data loss. The vulnerability also impacts compliance with security standards such as those outlined in the NIST Cybersecurity Framework, as it represents a critical weakness in input validation and command execution handling. Additionally, this vulnerability may be leveraged as part of broader attack chains, potentially serving as an initial compromise vector that allows attackers to establish persistent access or escalate privileges within the affected infrastructure.
Mitigation strategies for CVE-2008-4304 should prioritize immediate patching of phpCollab to versions that address this vulnerability, as the original software is no longer supported and maintained. Organizations should implement input validation controls that sanitize all environment variables before processing them, particularly those that may be influenced by user or client input. The implementation of proper parameterization and escaping mechanisms for any system calls or shell operations is essential to prevent command injection attacks. Network segmentation and access controls should be strengthened to limit exposure of vulnerable applications to untrusted networks. Security monitoring should be enhanced to detect unusual command execution patterns and potential exploitation attempts. Organizations should also consider implementing web application firewalls that can detect and block malicious input patterns associated with command injection attacks. The vulnerability's characteristics align with ATT&CK technique T1059.001 which covers command and scripting interpreter, and T1021.004 which involves remote services. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications and systems that may be susceptible to similar command injection flaws.