Re: Paypal Core Bug Bounty #3 - Persistent Web Vulnerability

[Krzysztof Kotowicz <kkotowicz+fd () gmail com>]

> Successful exploitation of the vulnerability results in persistent session
> hijacking (admin), account steal via persistent phishing or
> persistent search module web context manipulation.
Exactly how is the session hijacking/phishing/web content manipulation
_persistent_? Just because the payload is _stored_ does not necessarily
mean that is it always running.


> Proof of Concept:
> =================
> The persistent vulnerability can be exploited by remote attackers with
> privileged paypal user account and low required user interaction.


> [...]


> Manually reproduce ...
>
> 1. Go to the addressbook and switch to add a new contact to adressbook
> 2. Include script code (html/js) as username to the addressbook and save
> the context
> 2. Now, switch to the user search (addressbook) module (other layer) &
> click the user contact search to activate
> 3. Include the exact name of the username (script code (html/js)) from the
> addressbook and press the search button
> 4. The context of the other layer from the addressbook will be executed
> directly out of the results listing page of the exisiting user contacts
> 5. Done! POST REQUEST: method="post" name="searchContact"
How is THAT a "low user interaction" scenario? IIUC, victim has to manually
(no mention of CSRF here) insert a XSS payload into his address book, then
search for the payload exactly as inserted (is there a antiCSRF token
needed for the search request) and only then is the payload executed.
During this scenario user knowingly sees & uses Javascript code twice -
that's hardly low interaction.

Unless I'm missing something - is there a cross-account action going on
where one user manipulates the address book for a second user (e.g. from
the same organisation?)

Best regards,
Krzysztof Kotowicz

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