Updated:  March 21, 2006

Status

Affected

Vendor Statement

Subject: XSS Vulnerability in Pubcookie App Server Modules Author: Nathan Dors, Pubcookie Project Status: Confirmed, Patches Released Threat Class: Cross-Site Scripting Issue date: March 6, 2006 Severity: High Summary: New releases of Pubcookie are available to address Cross-Site Scripting (XSS) vulnerabilities found in the Pubcookie application server modules for Apache and Microsoft IIS. System administrators running a Pubcookie application server are strongly advised to read this security advisory and carry out the suggested actions below. Note: The URL for this security advisory is: http://pubcookie.org/news/20060306-apps-secadv.html Background: XSS vulnerabilities typically involve three principals: a vulnerable Web site, an attacker, and an end-user. The attacker exploits the vulnerability in the Web site such that script written by the attacker is run by the user within the security context of the Web site. XSS vulnerabilities can be classified as persistent or non-persistent, depending on whether or not the script or HTML injected by the attacker persists on the vulnerable Web site. A persistent XSS vulerability allows the attacker to leave script or HTML on the vulnerable Web site where it has the potential of being run by multiple users without further involvement by the attacker. Blogs and message boards are example places where persistent XSS vulnerabilities are often exploited. A non-persistent XSS vulnerability, on the other hand, doesn't allow the attacker to stage script or HTML on the vulnerable Web site. Instead, he or she must stage it elsewhere and then orchestrate some other means of initiating the attack, very often requiring the user's unintentional cooperation. Email, chat messages, and web pages are example places where script might be staged to help exploit a non-persistent XSS vulnerability. The user might trigger the attack simply by opening a tainted message or Web page, or by clicking inadvertently on a tainted link. Pubcookie Application Server Details: Non-persistent XSS vulnerabilities were found in the Pubcookie Apache module (mod_pubcookie) and ISAPI filter. These components mishandle untrusted data when printing responses to the browser. This makes them vulnerable to carefully crafted requests containing script or HTML. If an attacker can lure an unsuspecting user to visit carefully staged content, the attacker can use it to redirect the user to a vulnerable Pubcookie application server and attempt to exploit the XSS vulnerabilities. Threat Classification: These vulnerabilities are classified as *high* due to the nature and purpose of Pubcookie application servers for user authentication and Web Single Sign-on (SSO). An attacker who injects malicious script through the vulnerabilities might steal private Pubcookie data including a user's authentication assertion ("granting") cookies and application session cookies. Affected Versions: Apache module (mod_pubcookie): This advisory applies to the following versions of the Pubcookie Apache module (including beta and final releases): 1.x, 3.0.0, 3.1.0, 3.1.1, 3.2.0, 3.2.1, 3.2.1a and 3.3.0. ISAPI filter: This advisory applies to the following versions of the Pubcookie ISAPI filter (including beta and final releases): 3.1.0, 3.1.1, 3.2.1, 3.2.1a and 3.3.0. Patch Releases: The following patch releases address all known XSS vulnerabilities: * 3.3.0a (current production release; Unix and Windows) * 3.2.1b (Unix-only patch release) These releases are available now from the project's dowloads page: http://pubcookie.org/downloads.html Suggested Action: Application servers running an affected version should upgrade to one of the patch releases. Version 3.3.0a is the current production release. Note: For detailed version compatibility notes and upgrade information, consult the relevant Pubcookie application server documentation. Project Response: * 18 Dec 2005: Vulnerabilities discovered. * 18 Dec 2005: Initial contact with technical details of vulnerability. * 18 Dec 2005: Initial response confirming exploit and severity. * 05 Jan 2006: Initial patches available for hardness testing. * 06 Feb 2006: Solutions available for all known vulnerabilities. * xx Mar 2006: Coordinated public release of security advisory. Acknowledgements: The Pubcookie project wishes to thank Ben Maurer of Carnegie Mellon University for reporting the original XSS vulnerability and for advising during the fixes. The Pubcookie project also wishes to thank the following sites for their participation in the security response: University of Wisconsin-Madison, Carnegie Mellon University, Stockholm University, University of Virigina, University of Washington. References: Web Security Threat Classification http://www.webappsec.org/projects/threat/ CERT Advisory CA-2000-02 Malicious HTML Tags Embedded in Client Web Requests http://www.cert.org/advisories/CA-2000-02.html Phishing With Super Bait http://www.whitehatsec.com/presentations/phishing_superbait.pdf XSS (Cross Site Scripting) Cheat Sheet http://ha.ckers.org/xss.html

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.