CVE-2011-4821 in DIR-601
Summary
by MITRE
Directory traversal vulnerability in the TFTP server in D-Link DIR-601 Wireless N150 Home Router with firmware 1.02NA allows remote attackers to read arbitrary files via unspecified vectors.
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Analysis
by VulDB Data Team • 03/10/2019
The CVE-2011-4821 vulnerability represents a critical directory traversal flaw within the TFTP server implementation of D-Link DIR-601 Wireless N150 Home Router firmware version 1.02NA. This vulnerability exposes the device to remote exploitation where attackers can manipulate the TFTP service to access arbitrary files on the router's filesystem. The issue stems from inadequate input validation within the TFTP server component, allowing malicious actors to craft specific requests that bypass normal file access restrictions. Such directory traversal vulnerabilities typically arise when applications fail to properly sanitize user-supplied data before processing file system operations, creating opportunities for unauthorized access to sensitive system resources.
The technical exploitation of this vulnerability occurs through TFTP protocol interactions where attackers can manipulate file paths to navigate beyond the intended directory boundaries. This allows unauthorized access to configuration files, system logs, and potentially sensitive data stored within the router's file system. The vulnerability's impact is particularly severe given that TFTP servers are often used for firmware updates and network boot operations, making them attractive targets for attackers seeking persistent access or information gathering. The unspecified vectors mentioned in the description suggest that multiple attack paths may exist, potentially including various TFTP request formats or parameter manipulations that can trigger the directory traversal condition.
From an operational perspective, this vulnerability compromises the fundamental security posture of the affected router, potentially enabling attackers to extract sensitive configuration information, credentials, or system files that could facilitate further attacks. The remote nature of the vulnerability means that attackers do not require physical access to the device, making it particularly dangerous in network environments where routers are exposed to external traffic. This type of vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The attack vector falls under the MITRE ATT&CK framework's technique T1210, which covers exploitation of remote services for privilege escalation and information gathering.
Security mitigations for this vulnerability require immediate firmware updates from D-Link to address the directory traversal flaw in the TFTP server implementation. Network administrators should disable TFTP services on affected devices when not actively needed, as this reduces the attack surface for exploitation. Additionally, implementing network segmentation and access controls can limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of proper input validation and secure coding practices, particularly in embedded systems where resource constraints may lead to insufficient security controls. Organizations should also conduct regular vulnerability assessments of their network infrastructure to identify similar flaws in other devices and ensure timely patch management processes are in place to address such security weaknesses effectively.