CVE-2001-0520 in eSafe Gateway
Summary
by MITRE
Aladdin eSafe Gateway versions 3.0 and earlier allows a remote attacker to circumvent filtering of SCRIPT tags by embedding the scripts within certain HTML tags including (1) onload in the BODY tag, (2) href in the A tag, (3) the BUTTON tag, (4) the INPUT tag, or (5) any other tag in which scripts can be defined.
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Analysis
by VulDB Data Team • 12/21/2024
The CVE-2001-0520 vulnerability represents a critical web application security flaw in Aladdin eSafe Gateway versions 3.0 and earlier, which fundamentally undermines the security controls designed to protect against cross-site scripting attacks. This vulnerability specifically targets the HTML filtering mechanisms that are essential for preventing malicious script execution within web applications. The flaw allows remote attackers to bypass content filtering by exploiting the way the gateway processes certain HTML tags that can contain executable script code. The vulnerability is particularly concerning because it demonstrates a fundamental failure in the security model of the eSafe Gateway, which was designed to act as a protective barrier against malicious web content.
The technical implementation of this vulnerability stems from the gateway's inadequate handling of HTML event attributes and tag combinations that can contain script execution contexts. When processing HTML content, the eSafe Gateway fails to properly sanitize or filter script content embedded within specific HTML attributes such as onload in BODY tags, href in A tags, or various other tags including BUTTON and INPUT elements where script execution can occur. This represents a classic example of insecure input handling where the system does not adequately validate or sanitize user-provided content before allowing it to pass through the filtering mechanism. The vulnerability is classified under CWE-79 as a Cross-Site Scripting (XSS) flaw, specifically demonstrating how improper input validation can lead to security bypasses.
The operational impact of this vulnerability is severe as it allows attackers to execute arbitrary scripts in the context of a victim's browser session, potentially leading to session hijacking, data theft, or further exploitation of the target system. An attacker could craft malicious HTML content that appears legitimate but contains embedded scripts that bypass the gateway's filtering, thereby gaining unauthorized access to sensitive information or system resources. The vulnerability affects the core functionality of the security gateway, essentially rendering its filtering capabilities ineffective against certain types of script-based attacks. This vulnerability aligns with ATT&CK technique T1211 which involves exploiting vulnerabilities in web applications to execute malicious code, and represents a failure in the defense-in-depth principles that should protect against such attacks.
Organizations using Aladdin eSafe Gateway versions 3.0 and earlier should immediately implement mitigations including updating to patched versions of the software, implementing additional content filtering mechanisms, and conducting comprehensive security assessments of their web applications. The vulnerability highlights the importance of proper HTML sanitization and input validation in security gateways, and demonstrates why organizations should not rely solely on a single layer of security protection. Security administrators should also consider implementing additional monitoring and detection mechanisms to identify potential exploitation attempts and ensure that all HTML content is properly filtered regardless of the tag structure used. The incident underscores the critical need for regular security updates and the implementation of robust content validation controls to prevent similar bypass vulnerabilities in other security systems.