CVE-2010-3692 in phpCAS
Summary
by MITRE
Directory traversal vulnerability in the callback function in client.php in phpCAS before 1.1.3, when proxy mode is enabled, allows remote attackers to create or overwrite arbitrary files via directory traversal sequences in a Proxy Granting Ticket IOU (PGTiou) parameter.
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Analysis
by VulDB Data Team • 09/26/2021
The vulnerability described in CVE-2010-3692 represents a critical directory traversal flaw within the phpCAS library version 1.1.2 and earlier, specifically affecting systems operating in proxy mode. This weakness resides in the callback function implementation within the client.php file, where insufficient input validation allows malicious actors to manipulate file system operations through crafted Proxy Granting Ticket IOU parameters. The vulnerability is particularly dangerous because it enables remote attackers to execute arbitrary file system operations, potentially leading to unauthorized file creation or modification on the target system.
The technical exploitation of this vulnerability occurs when phpCAS operates in proxy mode, which is commonly used in single sign-on environments where applications need to authenticate users on behalf of other services. The flaw manifests when the system processes a PGTiou parameter containing directory traversal sequences such as "../" or similar constructs. These sequences are not properly sanitized or validated, allowing attackers to navigate outside the intended directory structure and target files in arbitrary locations on the file system. The vulnerability stems from improper input validation and inadequate path sanitization mechanisms within the callback processing logic, creating a direct path for malicious file system manipulation.
This directory traversal vulnerability has significant operational impact on systems utilizing phpCAS in proxy mode, potentially allowing attackers to overwrite critical system files, create backdoor access points, or execute arbitrary code through file injection techniques. The attack surface is particularly concerning in web applications where phpCAS is used for authentication, as it could enable attackers to compromise the entire authentication infrastructure. According to CWE-22, this vulnerability maps directly to improper limitation of a pathname to a restricted directory, a well-documented weakness that frequently leads to privilege escalation and system compromise. The impact extends beyond simple file manipulation, as successful exploitation could lead to complete system compromise, particularly when the affected application runs with elevated privileges.
The operational implications of CVE-2010-3692 align with several techniques documented in the MITRE ATT&CK framework, specifically mapping to T1078 for valid accounts and T1566 for credential access through exploitation of authentication systems. Organizations using vulnerable versions of phpCAS in proxy mode should immediately implement mitigations including patching to version 1.1.3 or later, implementing strict input validation for all PGTiou parameters, and restricting file system permissions for applications utilizing phpCAS. Additionally, network segmentation and monitoring for suspicious directory traversal patterns in application logs should be implemented to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in authentication libraries and the potential for seemingly minor flaws to create significant security risks in enterprise environments relying on single sign-on infrastructure.