I. BACKGROUND Taken from the Blojsom Website : "Blojsom is a Java-based, full-featured, multi-blog, multi-user software package that was inspired by blosxom. blojsom aims to retain a simplicity in design while adding flexibility in areas such as the flavors, templating, plugins, and the ability to run multiple blogs with a single blojsom installation" Blojsom is also the software running this blog and the software behind Apple Computer's OS X Server Weblog Server. http://wiki.blojsom.com/wiki/display/blojsom/About+blojsom II. DESCRIPTION Remote exploitation of a Cross-Site Scripting (XSS) vulnerability in Blojsom allows an attacker to force to inject arbitrary script code into a users session, possibly stealing logon credentials. To demonstrate the vulnerability, simply embed the following encoded text into the identified vulnerable fields. >'><script>alert(1234)</script> This will have the affect of popping up an alert window. This proof of concept could easily be altered to cause the script to return authentication credentials to an attacker controlled server. III. ANALYSIS Successful exploitation of this vulnerability would allow an attacker to inject arbitrary script code into the session. This could allow for the theft of authentication information, which could lead to a compromised account. In order for exploitation to occur, the targeted user would only have to view a blog entry from an attacker. This vulnerability has a high potential for widespread exploitation. IV. DETECTION Blojsom 2.3.1 Web application has been confirmed vulnerable. SNORT SIGNATURES alert tcp any any -> $HOME_NET $HTTP_PORTS (msg: "Blojsom Weblog XSS exploit"; flow:to_server; content:"POST"; depth:4; nocase; pcre:"/(blog-category-description|blog-entry-title|rss-enclosure-url|tec hnorati-tagsi|blog-category-name).*=.*%3cscript%3e.*%3c%2fscript%3e.*&/i "; classtype:web-application-activity; sid:9999994; rev:1;) V. WORKAROUND Cenzic is currently unaware of any effective workarounds that can be implemented on the server in order to mitigate the risk of this vulnerability; however, there are workarounds available for client protection. Since exploitation allows for the execution of malicious code in web browsers, successful exploitation could be thwarted by disabling script code and active content support within a client browser. Take note that employing this workaround could adversely affect web sites reliant upon the execution of browser-based script code. The following steps can be taken to disable active scripting in Mozilla and Internet Explorer: Internet Explorer 5.0, 5.01, 5.5, 6 a. On the Tools menu, click Internet Options, click the Security tab, click the Internet Web content zone, and then click Custom Level. b. In the Settings box, scroll down to the Scripting section, and click Disable under Active scripting and Scripting of Java applets. c. Click OK, and then click OK again. Mozilla Firefox a. On the Tools menu, click Options and click the Web Features tab. b. De-select the Enable JavaScript checkbox. c. Click OK. VI. VENDOR RESPONSE Fixed in CVS. The fixes will be made available in a blojsom 2.32 update. VII. CVE INFORMATION CERT has assigned a tracking number VU#425861. They take upto 45 days to make a public disclosure. VIII. DISCLOSURE TIMELINE 08/30/2006 Initial vendor notification 08/31/2006 Initial vendor response ??/??/???? Coordinated public disclosure IX. CREDIT Avinash Shenoi Cenzic Inc. X. LEGAL NOTICES Copyright &copy; Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of Cenzic. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email for permission. Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.