CVE-2005-2717 in WebCalendar
Summary
by MITRE
PHP remote file inclusion vulnerability in WebCalendar before 1.0.1 allows remote attackers to execute arbitrary PHP code when opening settings.php, possibly via send_reminders.php or other scripts.
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Analysis
by VulDB Data Team • 06/08/2019
The vulnerability identified as CVE-2005-2717 represents a critical remote file inclusion flaw in the WebCalendar application version 1.0.0 and earlier. This vulnerability resides within the application's handling of user-supplied input that is directly incorporated into file inclusion operations, creating a pathway for remote attackers to execute arbitrary PHP code on the target system. The flaw specifically manifests when the application processes parameters that control which files to include or require, allowing malicious input to alter the intended file inclusion behavior.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters that are used in PHP's include or require functions. When attackers can control the value of these parameters, they can redirect the application to include malicious PHP files hosted on remote servers. In the context of WebCalendar, the vulnerability becomes particularly dangerous when attackers can influence the inclusion process through scripts like send_reminders.php or other vulnerable endpoints that accept user-controllable parameters. This type of vulnerability falls under the CWE-88 category, which describes improper neutralization of special elements used in an expression, specifically addressing the issue of command injection through improper input handling.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with complete control over the affected web server. Successful exploitation allows adversaries to upload and execute malicious code, potentially leading to full system compromise, data exfiltration, or the establishment of persistent backdoors. The vulnerability affects the application's configuration and settings files, particularly settings.php, which when compromised can lead to unauthorized modification of calendar settings, user access controls, or other critical system parameters. Attackers can leverage this vulnerability to escalate privileges, modify database contents, or even use the compromised server as a launch point for further attacks against internal networks.
Security practitioners should implement multiple layers of defense to protect against this vulnerability, starting with immediate patching to version 1.0.1 or later where the issue has been addressed. Input validation and sanitization mechanisms should be strengthened to prevent user-supplied data from being directly used in file inclusion operations. The principle of least privilege should be enforced by ensuring that web applications run with minimal required permissions and that file inclusion operations use absolute paths rather than user-controllable variables. Additionally, implementing web application firewalls and runtime application self-protection mechanisms can provide additional protection layers. Organizations should also conduct regular security assessments and maintain up-to-date vulnerability scanning to identify similar issues in other applications. This vulnerability demonstrates the critical importance of proper input validation and the dangers of allowing user-controllable parameters to influence system-level operations, aligning with ATT&CK technique T1190 for exploitation of remote services and T1059 for execution through command and scripting interfaces.