AOH :: HP Unsorted B :: B06-4719.HTM

Blojsom XSS



XSS vulnerability in Blojsom
XSS vulnerability in Blojsom





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.

>'>

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|technorati-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 =A9

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