Advisory ID: HTB23235
Product: Google Calendar Events WordPress plugin
Vendor: Phil Derksen
Vulnerable Version(s): 2.0.1 and probably prior
Tested Version: 2.0.1
Advisory Publication:  September 17, 2014  [without technical details]
Vendor Notification: September 17, 2014 
Vendor Patch: October 7, 2014 
Public Disclosure: October 8, 2014 
Vulnerability Type: Cross-Site Scripting [CWE-79]
CVE Reference: CVE-2014-7138
Risk Level: Low 
CVSSv2 Base Score: 2.6 (AV:N/AC:H/Au:N/C:N/I:P/A:N)
Solution Status: Fixed by Vendor
Discovered and Provided: High-Tech Bridge Security Research Lab ( https://www.htbridge.com/advisory/ ) 

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Advisory Details:

High-Tech Bridge Security Research Lab discovered vulnerability in Google Calendar Events WordPress plugin, which can be exploited to perform Cross-Site Scripting (XSS) attacks against administrator of a WordPress website with vulnerable plugin.


1) Reflected Cross-Site Scripting (XSS) in Google Calendar Events WordPress Plugin: CVE-2014-7138

Input passed via the "gce_feed_ids" HTTP GET parameter to "/wp-admin/admin-ajax.php" script is not properly sanitised before being returned to the user. A remote attacker can trick a logged-in administrator to open a specially crafted link and execute arbitrary HTML and script code in browser in context of the vulnerable website.

The exploitation example below uses the "alert()" JavaScript function to display "immuniweb" word:

https://wordpress/wp-admin/admin-ajax.php?action=gce_ajax&gce_type=page&gce_feed_ids=%27%22%3E%3Cscript%3Ealert%28/immuniweb/%29;%3C/script%3E



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Solution:

Update to Google Calendar Events 2.0.4

More Information:
https://github.com/pderksen/WP-Google-Calendar-Events/commit/df1fe1d71f8ce9496cc601c96839c474e49db91d
https://github.com/pderksen/WP-Google-Calendar-Events/commit/a701ceeb410bdda9d96c9d3d12104630df5d5b43

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References:

[1] High-Tech Bridge Advisory HTB23235 - https://www.htbridge.com/advisory/HTB23235 - Reflected Cross-Site Scripting (XSS) in Google Calendar Events WordPress Plugin.
[2] Google Calendar Events WordPress plugin - https://philderksen.com/ - Parses Google Calendar feeds and displays the events as a calendar grid or list on a page, post or widget.
[3] Common Vulnerabilities and Exposures (CVE) - https://cve.mitre.org/ - international in scope and free for public use, CVE® is a dictionary of publicly known information security vulnerabilities and exposures.
[4] Common Weakness Enumeration (CWE) - https://cwe.mitre.org - targeted to developers and security practitioners, CWE is a formal list of software weakness types.
[5] ImmuniWeb® SaaS - https://www.htbridge.com/immuniweb/ - hybrid of manual web application penetration test and cutting-edge vulnerability scanner available online via a Software-as-a-Service (SaaS) model.

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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.