CVE-2009-4471 in FreeSchool
Summary
by MITRE
Multiple PHP remote file inclusion vulnerabilities in FreeSchool 1.1.0 and earlier allow remote attackers to execute arbitrary PHP code via a URL in the CLASSPATH parameter to (1) bib_form.php, (2) bib_pldetails.php, (3) bib_plform.php, (4) bib_plsearchc.php, (5) bib_plsearchs.php, (6) bib_save.php, (7) bib_searchc.php, (8) bib_searchs.php, (9) edi_form.php, (10) edi_save.php, (11) gen_form.php, (12) gen_save.php, (13) lin_form.php, (14) lin_save.php, (15) luo_form.php, (16) luo_save.php, (17) sog_form.php, or (18) sog_save.php in biblioteca/; (19) cal_insert.php, (20) cal_save.php, or (21) cal_saveactivity.php in calendario/; (22) circolari/cir_save.php; or (23) modulistica/mdl_save.php.
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability described in CVE-2009-4471 represents a critical remote file inclusion flaw affecting the FreeSchool educational management system version 1.1.0 and earlier. This vulnerability resides in multiple PHP scripts across various directories within the application's file structure, specifically targeting the biblioteca/, calendario/, circolari/, and modulistica/ directories. The flaw stems from improper input validation and sanitization of user-supplied parameters, particularly the CLASSPATH parameter that is processed without adequate security controls. This allows malicious actors to inject arbitrary URLs that are subsequently included and executed by the PHP interpreter, creating a pathway for remote code execution.
The technical implementation of this vulnerability aligns with CWE-88, which describes improper neutralization of special elements used in an expression, and more specifically CWE-94, which addresses the execution of arbitrary code or commands. The vulnerability operates through a classic remote file inclusion attack vector where an attacker can manipulate the CLASSPATH parameter to point to malicious PHP scripts hosted on remote servers. When the vulnerable PHP scripts process this parameter, they use functions like include() or require() without proper validation, directly incorporating external content into the application's execution context. This creates a scenario where attackers can execute arbitrary PHP code with the privileges of the web server process, potentially leading to complete system compromise.
The operational impact of this vulnerability is severe and multifaceted, representing a critical threat to the confidentiality, integrity, and availability of the affected FreeSchool deployment. Attackers can leverage this vulnerability to gain unauthorized access to the system, potentially escalating privileges to execute system commands, access sensitive data, or establish persistent backdoors. The attack surface is particularly broad as it affects 23 different PHP scripts across multiple functional modules, increasing the likelihood of successful exploitation. This vulnerability directly maps to several ATT&CK techniques including T1190 for exploitation of remote services and T1059 for execution of code through command and scripting interpreters. The implications extend beyond immediate code execution to include potential data breaches, system infiltration, and the possibility of lateral movement within network environments where the vulnerable system resides.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements. The primary solution involves implementing strict input validation and sanitization for all user-supplied parameters, particularly those used in file inclusion operations. Developers should avoid using user-controllable variables directly in include or require statements, instead implementing whitelisting mechanisms that only permit known good values. The application should be upgraded to FreeSchool version 1.1.1 or later, which contains the necessary patches to address this vulnerability. Additionally, security measures such as disabling remote file inclusion in PHP configuration, implementing proper access controls, and conducting regular security code reviews should be enforced. Network-level protections including firewall rules and web application firewalls can provide additional layers of defense against exploitation attempts, while regular vulnerability assessments and security monitoring should be implemented to detect potential exploitation attempts.