CVE-2000-0591 in BorderManager
Summary
by MITRE
Novell BorderManager 3.0 and 3.5 allows remote attackers to bypass URL filtering by encoding characters in the requested URL.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability identified as CVE-2000-0591 represents a significant security flaw in Novell BorderManager versions 3.0 and 3.5 that directly impacts web content filtering mechanisms. This issue stems from inadequate input validation within the URL processing subsystem, allowing malicious actors to circumvent established security policies through simple character encoding techniques. The flaw operates at the application layer and specifically targets the URL filtering capabilities that organizations rely upon to control web access and prevent unauthorized content access.
The technical implementation of this vulnerability exploits the inconsistent handling of URL encoding by the BorderManager software. When users request web resources, the system should properly decode and validate all URL components against configured filtering rules. However, the software fails to consistently process encoded characters such as percent-encoding sequences, allowing attackers to embed malicious content within seemingly benign URLs. This occurs because the filtering engine does not perform comprehensive decoding of all URL components before applying security policies, creating a bypass path for potentially harmful web requests. The vulnerability specifically relates to CWE-180, which addresses incorrect behavior in input validation, and CWE-20, covering input validation issues that can lead to various security consequences.
From an operational standpoint, this vulnerability poses substantial risk to organizations deploying Novell BorderManager for web content filtering and security control. Attackers can exploit this weakness to access restricted websites, bypass corporate web policies, and potentially gain access to malicious content that would normally be blocked. The impact extends beyond simple policy bypass, as it undermines the fundamental security posture of organizations relying on the software for network protection. This vulnerability is particularly concerning in enterprise environments where web filtering serves as a critical defense mechanism against malware distribution, inappropriate content access, and data exfiltration attempts. The remote nature of the attack means that threat actors do not require physical access to the network or administrative privileges to exploit this flaw.
The exploitation of this vulnerability aligns with several techniques documented in the ATT&CK framework, particularly those related to evasion and privilege escalation. Adversaries can leverage this weakness to bypass network-level controls and move laterally within networks, potentially accessing sensitive resources or establishing persistent access points. The vulnerability also represents a bypass of defensive controls that would normally be in place to protect against web-based threats, making it particularly dangerous in environments where BorderManager serves as a primary security control. Organizations should note that this vulnerability affects the core functionality of the software, meaning that any security policies implemented through the filtering system become ineffective against properly crafted malicious URLs.
Mitigation strategies should focus on immediate software updates and patches provided by Novell to address the URL encoding validation issues. Organizations should also implement additional monitoring and logging of web traffic to detect anomalous URL patterns that might indicate exploitation attempts. Network administrators should consider implementing secondary filtering mechanisms or alternative security solutions to provide layered protection against this type of bypass attack. The implementation of comprehensive URL inspection and validation policies, combined with regular security assessments of web filtering systems, can help prevent exploitation of similar vulnerabilities in the future. Additionally, organizations should conduct thorough security reviews of all network filtering and content control systems to identify and remediate potential encoding-related issues that could create similar bypass opportunities for attackers.