CVE-2001-0897 in Ultimate Bulletin Board
Summary
by MITRE
Cross-site scripting vulnerability in Infopop Ultimate Bulletin Board (UBB) before 5.47e allows remote attackers to steal user cookies via an [IMG] tag that references an about: URL with an onerror field.
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Analysis
by VulDB Data Team • 10/01/2025
The vulnerability described in CVE-2001-0897 represents a classic cross-site scripting flaw that existed within the Infopop Ultimate Bulletin Board software prior to version 5.47e. This type of vulnerability falls under the CWE-79 category of Cross-Site Scripting, which occurs when web applications fail to properly validate or sanitize user input before rendering it in web pages. The specific implementation flaw in this case involved the processing of [IMG] tags within the bulletin board's message parsing system, creating a dangerous pathway for malicious actors to inject client-side scripts into web pages viewed by other users.
The technical mechanism of exploitation in this vulnerability relies on the improper handling of image tags that reference about: URLs, which are special URLs used by web browsers for internal operations. When an attacker crafts a message containing an [IMG] tag that points to an about: URL with an onerror attribute, the browser attempts to load the malformed image reference, triggering the execution of the JavaScript code embedded within the onerror field. This particular attack vector demonstrates how seemingly innocuous HTML elements can be weaponized when input validation is insufficient, allowing attackers to execute arbitrary scripts in the context of the victim's browser session.
The operational impact of this vulnerability extends beyond simple script execution to include session hijacking and credential theft through cookie manipulation. Since the attack allows remote attackers to steal user cookies, it provides unauthorized access to user sessions on the bulletin board platform, potentially enabling full account compromise. This type of attack aligns with ATT&CK technique T1531 which involves modifying or hijacking existing processes to gain access to systems. The vulnerability essentially provides attackers with a means to establish persistent access to user accounts, making it particularly dangerous for platforms that rely heavily on user authentication and session management.
The security implications of this flaw highlight the critical importance of input validation and output encoding in web application security. The vulnerability demonstrates how improper sanitization of user-provided content can create persistent security risks that affect all users of the platform. Organizations running legacy bulletin board systems would have been particularly vulnerable, as the attack does not require any special privileges or complex exploitation techniques beyond crafting malicious posts. This makes the vulnerability particularly dangerous in multi-user environments where users may inadvertently click on malicious content or where administrators may not have adequate monitoring in place to detect such attacks.
Mitigation strategies for this vulnerability would have required immediate patching of the affected software to implement proper input validation for image tag attributes and URL handling. The solution would involve implementing strict sanitization routines that prevent the execution of JavaScript code within image tag attributes, particularly those referencing about: URLs or other special browser protocols. Additionally, organizations should have implemented content security policies and regular security audits to detect similar vulnerabilities in other components of their web applications. The vulnerability also underscores the importance of maintaining up-to-date software versions and implementing comprehensive security testing procedures that include cross-site scripting vulnerability assessments.