CVE-2008-4133 in DIR
Summary
by MITRE
The web proxy service on the D-Link DIR-100 with firmware 1.12 and earlier does not properly filter web requests with large URLs, which allows remote attackers to bypass web restriction filters.
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Analysis
by VulDB Data Team • 12/08/2024
The D-Link DIR-100 wireless router represents a critical security vulnerability in network infrastructure devices where the web proxy service fails to adequately validate incoming HTTP requests. This flaw exists specifically within firmware versions 1.12 and earlier, creating an exploitable condition that directly impacts the device's ability to enforce web content filtering policies. The vulnerability stems from insufficient input validation mechanisms that permit malformed or excessively long URL requests to pass through the proxy service without proper sanitization, thereby undermining the intended security controls designed to restrict access to specific web resources.
The technical implementation of this vulnerability manifests through improper handling of URL length parameters within the proxy service's request processing pipeline. When remote attackers submit web requests containing unusually long URLs, the system fails to implement appropriate bounds checking or request length validation that would normally prevent such requests from being processed. This weakness creates a bypass condition where malicious actors can craft specially formatted URLs that exceed normal processing limits, allowing them to circumvent the device's configured web filtering rules. The flaw operates at the application layer of the network stack, specifically within the HTTP proxy component that handles web traffic routing and filtering decisions.
Operationally, this vulnerability presents significant risks to organizations relying on D-Link DIR-100 devices for network security enforcement. Attackers can exploit this condition to access restricted websites, bypass corporate web filtering policies, and potentially gain access to malicious content that would normally be blocked. The impact extends beyond simple content bypass, as this weakness could enable more sophisticated attacks including web-based malware delivery, phishing attempts, or unauthorized access to sensitive internal resources. The vulnerability affects the fundamental security posture of networks using these devices, particularly in enterprise environments where web filtering is critical for maintaining security compliance and protecting against malicious web traffic.
Security mitigations for this vulnerability should prioritize immediate firmware updates to versions that address the URL length validation issue, as recommended by D-Link's security advisories. Network administrators should implement additional monitoring controls to detect anomalous URL patterns and unusual web traffic behavior that might indicate exploitation attempts. The vulnerability aligns with CWE-122, which describes insufficient input validation, and represents a classic example of how inadequate bounds checking can lead to security bypass conditions. From an ATT&CK framework perspective, this vulnerability maps to techniques involving proxy bypass and network egress filtering evasion, making it particularly concerning for organizations implementing network-based security controls. Organizations should also consider implementing additional network segmentation and traffic monitoring to detect and prevent exploitation attempts while awaiting firmware updates.