CVE-2007-2236 in PunBB
Summary
by MITRE
footer.php in PunBB 1.2.14 and earlier allows remote attackers to include local files in include/user/ via a cross-site scripting (XSS) attack, or via the pun_include tag, as demonstrated by use of admin_options.php to execute PHP code from an uploaded avatar file.
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Analysis
by VulDB Data Team • 08/29/2018
The vulnerability identified as CVE-2007-2236 affects PunBB version 1.2.14 and earlier, representing a critical security flaw in the forum software's file inclusion mechanism. This issue stems from inadequate input validation and sanitization within the footer.php component, which processes user-provided data without proper security checks. The vulnerability manifests through two primary attack vectors that demonstrate the severity of the flaw in the context of web application security.
The technical implementation of this vulnerability involves the improper handling of user-controllable input parameters that are passed to the include/user/ directory. Attackers can exploit this weakness through cross-site scripting techniques or by leveraging the pun_include tag functionality, which creates a pathway for arbitrary file inclusion attacks. When an attacker successfully manipulates the input parameters, they can cause the application to include local files from the server's file system, potentially leading to unauthorized code execution. This represents a classic local file inclusion vulnerability that can be escalated through various attack methods, including the use of admin_options.php to execute PHP code from uploaded avatar files, demonstrating how the flaw can be chained with other exploitation techniques.
The operational impact of this vulnerability extends beyond simple data theft or service disruption, as it can enable complete system compromise. An attacker who successfully exploits this vulnerability gains the ability to execute arbitrary PHP code on the target server, potentially allowing them to establish persistent backdoors, escalate privileges, or access sensitive user data. The vulnerability particularly affects environments where PunBB is deployed with default configurations or where administrators have not implemented additional security measures. The inclusion of uploaded avatar files as a vector for code execution highlights the dangerous combination of file upload functionality and insecure file handling practices, creating a pathway for attackers to execute malicious code with the privileges of the web server.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and sanitization mechanisms throughout the application. The most effective approach involves removing or properly escaping user-controllable parameters before they are processed by the include functions, which directly addresses the root cause identified in CWE-22 and CWE-94. Organizations should also implement proper file upload restrictions and validation to prevent malicious files from being stored on the server. Additionally, the principle of least privilege should be enforced by running the web application with minimal necessary permissions and by implementing proper access controls for sensitive directories. The ATT&CK framework categorizes this vulnerability under T1059 for execution through PHP code injection, making it a critical target for defensive measures including web application firewalls, regular security assessments, and proper code review processes to prevent similar issues in future deployments.