CVE-2013-4658 in EA6500
Summary
by MITRE
Linksys EA6500 has SMB Symlink Traversal allowing symbolic links to be created to locations outside of the Samba share.
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Analysis
by VulDB Data Team • 01/27/2024
The CVE-2013-4658 vulnerability affects Linksys EA6500 routers running Samba file sharing services, presenting a critical symbolic link traversal flaw that enables unauthorized access to system directories beyond the intended Samba share boundaries. This vulnerability stems from insufficient input validation within the Samba implementation on the affected router firmware, allowing malicious actors to create symbolic links that point to arbitrary filesystem locations. The flaw specifically manifests in the SMB/CIFS file sharing protocol handling where the system fails to properly sanitize path references during symbolic link creation operations. This vulnerability represents a classic path traversal attack vector that can be exploited to bypass normal access controls and potentially gain unauthorized access to sensitive system files, configuration data, and user information stored outside the designated shared directories.
The technical implementation of this vulnerability occurs at the Samba server level within the router's firmware, where symbolic link creation functionality does not adequately validate the target paths of the links being created. When a user or attacker attempts to create a symbolic link through the SMB protocol, the system accepts the link creation request without properly verifying that the target path remains within the confines of the designated Samba share. This allows an attacker to create symbolic links pointing to system directories such as /etc, /var, or other sensitive locations that contain configuration files, authentication data, or other critical system resources. The vulnerability is particularly concerning because it operates at the file system level and can be exploited without requiring elevated privileges, making it accessible to any user who can establish an SMB connection to the affected router.
The operational impact of CVE-2013-4658 extends beyond simple unauthorized file access, as it creates a potential pathway for complete system compromise and data exfiltration. Attackers can leverage this vulnerability to access router configuration files that may contain administrative credentials, network settings, and other sensitive information that could be used for further attacks. The ability to traverse symbolic links also enables potential privilege escalation attacks, where an attacker might gain access to system-level files that should normally be restricted to authorized administrators only. This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and represents a fundamental flaw in access control enforcement within network device file sharing services. The impact is particularly severe in environments where the router serves as a central file sharing point for multiple users or departments, as it could enable widespread unauthorized access to shared resources and sensitive data.
Mitigation strategies for CVE-2013-4658 should focus on immediate firmware updates from Linksys to address the underlying Samba implementation flaw, as well as network-level security measures to limit access to the affected SMB services. Organizations should disable SMB file sharing on the router if it is not essential for operations, and implement network segmentation to isolate the router from critical systems. Additional protective measures include monitoring SMB traffic for suspicious symbolic link creation attempts and implementing proper access controls that limit who can establish SMB connections to the device. From an ATT&CK framework perspective, this vulnerability maps to T1078 Valid Accounts and T1566 Phishing, as it could be exploited through legitimate user accounts to gain unauthorized access to system resources. The vulnerability also relates to T1005 Data from Local System, as it enables extraction of sensitive information from the target system. Network administrators should also consider implementing firewall rules that restrict SMB port access to trusted IP addresses only, and conduct regular security audits to identify any unauthorized symbolic link creation activities on network devices.