If a user does not specify a "canonical" URL on installation of concrete5, unauthenticated remote attackers can write to the
"collectionversionblocksoutputcache" table of the MySQL Database, by making HTTP GET request with a poisoned HOST header.
Some affected concrete5 webpages can then potentially render arbitrary links that can point to a malicious website.
Example MySQL data from "CollectionVersionBlocksOutputCache" table.
(164, 1, 57, 'Header Site Title', '<a href="http://attacker-ip/concrete5-8.1.0/index.php" id="header-site-title">Elemental</a>', 1649861489
c:\> curl -v http://VICTIM-IP/concrete5-8.1.0/index.php/services -H "Host: attacker-ip" | more
Click on links in header portion of the webpage from one of the above URLs.
Team / Drop down Menu
click on the links on footer portion of the webpage.
FAQ / Help
View on Google Maps
Result: user gets redirected to attacker-ip.
Vendor Notification : April 11, 2017
Vendor reply: "this is a known issue" : April 12, 2017
Requested a CVE from mitre.
CVE assigned : April 12, 2017
April 13, 2017 : Public Disclosure
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