CVE-2010-3691 in phpCAS
Summary
by MITRE
PGTStorage/pgt-file.php in phpCAS before 1.1.3, when proxy mode is enabled, allows local users to overwrite arbitrary files via a symlink attack on an unspecified file.
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Analysis
by VulDB Data Team • 09/26/2021
The vulnerability identified as CVE-2010-3691 affects phpCAS versions prior to 1.1.3 and specifically targets the PGTStorage/pgt-file.php component when proxy mode is enabled. This represents a critical security flaw that enables local attackers to perform arbitrary file overwrites through a symbolic link attack mechanism. The vulnerability stems from insufficient validation of file operations within the proxy grant ticket storage functionality, creating an exploitable condition that can be leveraged by malicious users with local system access.
The technical implementation of this vulnerability involves a race condition or improper file handling mechanism that allows attackers to manipulate symbolic links in the file system. When phpCAS operates in proxy mode, it creates and manages proxy grant tickets stored in files within the PGTStorage directory. The flaw occurs during the file creation or modification process where the application does not properly validate or sanitize the target file paths, enabling attackers to substitute legitimate files with symbolic links pointing to sensitive system locations. This type of attack falls under the category of symlink-based file overwrite vulnerabilities that are commonly classified under CWE-59 and CWE-377.
From an operational perspective, this vulnerability presents significant risks to systems utilizing phpCAS for single sign-on authentication with proxy capabilities. The local user access requirement means that attackers must already have system-level privileges or have compromised a local account to exploit this flaw. However, the potential impact is substantial as successful exploitation can result in arbitrary file overwrites, which may lead to privilege escalation, data corruption, or unauthorized modification of critical system files. The vulnerability directly impacts the integrity and confidentiality of authentication systems that rely on phpCAS for secure proxy authentication mechanisms.
The attack vector for CVE-2010-3691 aligns with techniques documented in the MITRE ATT&CK framework under the T1059.007 sub-technique for Unix Shell and T1068 for Exploitation for Privilege Escalation. Organizations using affected phpCAS versions face potential compromise of their authentication infrastructure, particularly in environments where proxy authentication is utilized for web applications. The vulnerability affects the principle of least privilege and can undermine the security posture of systems that depend on proper file access controls and authentication mechanisms. Security practitioners should consider this vulnerability in their risk assessments for web application security and authentication system integrity.
Mitigation strategies for this vulnerability include immediate upgrade to phpCAS version 1.1.3 or later, which contains the necessary patches to address the symbolic link handling issues. Additionally, system administrators should implement proper file permissions and access controls to limit local user privileges where possible. The remediation process should include thorough review of file system permissions for the PGTStorage directory and related components, ensuring that the application operates with minimal required privileges. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other authentication components and web applications within the organization's infrastructure.