Advisory ID: HTB23264
Product: Paid Memberships Pro WordPress plugin
Vendor: Stranger Studios 
Vulnerable Version(s): 1.8.4.2 and probably prior
Tested Version: 1.8.4.2
Advisory Publication:  July 1, 2015  [without technical details]
Vendor Notification: July 1, 2015 
Vendor Patch: July 8, 2015 
Public Disclosure: July 22, 2015 
Vulnerability Type: Cross-Site Scripting [CWE-79]
CVE Reference: CVE-2015-5532
Risk Level: Medium 
CVSSv2 Base Score: 4.3 (AV:N/AC:M/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 Paid Memberships Pro WordPress plugin, which can be exploited to perform Cross-Site Scripting (XSS) attacks against website administrators.


1) Cross-Site Scripting (XSS) in Paid Memberships Pro WordPress plugin: CVE-2015-5532

1.1 Input passed via "s" HTTP GET parameter to "/wp-admin/admin.php" (when "page" is set to "pmpro-membershiplevels") 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:

http://[host]/wp-admin/admin.php?page=pmpro-membershiplevels&s=%22%3E%3Cscript%3Ealert%28%27ImmuniWeb%27%29;%3C/script%3E

1.2 Input passed via "edit" HTTP GET parameter to "/wp-admin/admin.php" (when "page" is set to "pmpro-membershiplevels") 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:

http://[host]/wp-admin/admin.php?page=pmpro-membershiplevels&edit=%22%3E%3Cscript%3Ealert%28%27ImmuniWeb%27%29;%3C/script%3E

1.3 Input passed via "s" HTTP GET parameter to "/wp-admin/admin.php" (when "page" is set to "pmpro-memberslist") 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:

http://[host]/wp-admin/admin.php?l&page=pmpro-memberslist&s=%22%3E%3Cscript%3Ealert%28%27ImmuniWeb%27%29;%3C/script%3E

1.4 Input passed via "s" HTTP GET parameter to "/wp-admin/admin.php" (when "page" is set to "pmpro-orders") 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:

http://[host]/wp-admin/admin.php?filter=all&start-month=1&start-day=1&start-year=2015&end-month=6&end-day=22&end-year=2015&predefined-date=This+Month&l=1&status&page=pmpro-orders&s=%22%3E%3Cscript%3Ealert%28%27immuniweb%27%29;%3C/script%3E

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Solution:

Update to Paid Memberships Pro 1.8.4.3

More Information:
http://www.paidmembershipspro.com/2015/07/pmpro-updates-1-8-4-3-and-1-8-4-4/
https://github.com/strangerstudios/paid-memberships-pro/commit/add03e3ed90e9163e5a46e20e6c371a87ff5a677

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References:

[1] High-Tech Bridge Advisory HTB23264 - https://www.htbridge.com/advisory/HTB23264 - Multiple XSS Vulnerabilities in Paid Memberships Pro WordPress Plugin.
[2] Paid Memberships Pro WordPress plugin - http://www.strangerstudios.com/ - Paid Memberships Pro is the community solution for adding paid memberships to your WordPress site.
[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.
[4] Common Weakness Enumeration (CWE) - http://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.