CVE-2006-1291 in PHP iCalendar
Summary
by MITRE
publish.ical.php in Jim Hu and Chad Little PHP iCalendar 2.21 and earlier does not require authentication for write access to the calendars directory, which allows remote attackers to upload and execute arbitrary PHP scripts via a WebDAV PUT request with a filename containing a .php extension and a trailing null character.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability described in CVE-2006-1291 represents a critical authentication bypass flaw within the Jim Hu and Chad Little PHP iCalendar 2.21 software suite. This issue specifically affects the publish.ical.php component which fails to properly validate user credentials before granting write permissions to the calendar directory structure. The vulnerability stems from inadequate input validation and access control mechanisms that permit unauthenticated remote attackers to exploit WebDAV PUT operations without proper authorization. This flaw exists at the application level and directly violates fundamental security principles of authentication and authorization controls.
The technical exploitation of this vulnerability occurs through a carefully crafted WebDAV PUT request that includes a filename with a .php extension combined with a trailing null character. This specific combination allows attackers to bypass the application's file extension validation checks and successfully upload malicious PHP scripts to the targeted calendar directory. The trailing null character manipulation exploits buffer handling weaknesses in the file processing logic, enabling the execution of arbitrary code on the vulnerable server. This technique demonstrates a sophisticated understanding of how to manipulate HTTP request parameters to circumvent security controls, aligning with attack patterns documented in the ATT&CK framework under privilege escalation and execution techniques.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with complete server compromise capabilities through remote code execution. Once successfully exploited, attackers can upload backdoor scripts, modify existing calendar data, escalate privileges, and potentially establish persistent access to the compromised system. The vulnerability affects the entire calendar directory structure, meaning that any calendar data stored in this location becomes vulnerable to unauthorized modification or complete destruction. This creates significant business continuity risks for organizations relying on the affected iCalendar software for scheduling and calendar management functions.
Organizations should immediately implement comprehensive mitigations including immediate patching of the affected PHP iCalendar software to version 2.22 or later, which contains the necessary authentication controls. Network-level protections should be implemented through firewall rules that restrict access to WebDAV endpoints and the calendar directory, while also implementing proper authentication mechanisms for all file upload operations. Input validation should be strengthened to prevent null character injection attacks, and proper access control lists should be configured to ensure that only authorized users can write to calendar directories. The vulnerability aligns with CWE-285, which addresses improper authorization issues, and represents a clear violation of the principle of least privilege that should be enforced in all web applications. Additionally, organizations should conduct thorough security audits of all web applications to identify similar authentication bypass vulnerabilities that may exist in other components of their infrastructure.