Buyspeed Cross-site Scripting

Periscope BuySpeed version 14.5 is vulnerable to stored cross-site scripting, which could allow a local, authenticated attacker to store arbitrary JavaScript within the application. This JavaScript is subsequently displayed by the application without sanitization and is executed in the browser of the user, which could possibly cause website redirection, session hijacking, or information disclosure. This vulnerability has been patched in BuySpeed version 15.3. (2020-04-10, CVE-2020-9056)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>