CVE-2001-1157 in WEBsweeper
Summary
by MITRE
Baltimore Technologies WEBsweeper 4.0 and 4.02 does not properly filter Javascript from HTML pages, which could allow remote attackers to bypass the filtering via (1) an extra leading < and one or more characters before the SCRIPT tag, or (2) tags using Unicode.
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Analysis
by VulDB Data Team • 09/27/2025
The vulnerability identified as CVE-2001-1157 affects Baltimore Technologies WEBsweeper versions 4.0 and 4.02, representing a critical security flaw in web application security filtering mechanisms. This weakness resides in the software's inability to properly sanitize javascript code from html content, creating a pathway for malicious actors to circumvent intended security protections. The vulnerability specifically targets the input validation and sanitization processes that should prevent cross-site scripting attacks by removing or escaping potentially harmful javascript code from user-submitted content.
The technical implementation of this flaw allows attackers to exploit multiple bypass techniques that circumvent the filtering mechanisms. The first method involves prepending an extra leading less-than sign followed by one or more characters before the SCRIPT tag, effectively confusing the filtering algorithm into incorrectly processing the malicious code. The second technique utilizes unicode encoding to encode the script tags, making them invisible to standard filtering mechanisms that may not properly decode or recognize these encoded sequences. This demonstrates a fundamental weakness in the sanitization process that fails to account for various encoding methods and malformed input sequences that could be used to evade detection.
The operational impact of this vulnerability extends beyond simple bypassing of security measures, as it enables remote attackers to execute malicious javascript code within the context of vulnerable web applications. This capability allows threat actors to perform actions such as stealing user session cookies, redirecting users to malicious sites, injecting additional malicious content, or performing other cross-site scripting attacks that could compromise user data and system integrity. The vulnerability essentially undermines the core purpose of the WEBsweeper application, which is to provide security filtering for web content, by allowing attackers to inject javascript code that bypasses all intended protection mechanisms.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting (XSS) flaws in software applications, and demonstrates the specific weakness in input sanitization that allows attackers to bypass security controls. From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for Scripting and T1566 for Phishing, as attackers can leverage this flaw to deliver malicious scripts to users and potentially gain unauthorized access to sensitive information. The vulnerability also reflects poor input validation practices that violate security best practices established in various industry standards and frameworks. Organizations using affected versions of WEBsweeper face significant risk of data breaches and compromised user sessions, as this flaw provides attackers with a direct method to inject malicious code into web applications without requiring additional exploitation techniques. The remediation approach requires immediate patching of the software to address the filtering implementation issues and implementation of more robust input validation mechanisms that can properly detect and neutralize encoded or malformed javascript sequences.
The vulnerability highlights the importance of comprehensive security testing, particularly around input validation and sanitization processes, as well as the necessity of implementing defense-in-depth strategies that account for multiple bypass techniques. Organizations should also consider implementing additional security controls such as content security policies, web application firewalls, and regular security assessments to mitigate risks associated with similar vulnerabilities in their web applications.