Full Disclosure mailing list archives

Re: Google open redirect


From: Luis Santana <hacktalkblog () gmail com>
Date: Thu, 8 Dec 2011 01:05:10 -0500

As for minimal risk I personally don't agree. I have leveraged Unvalidated
URL Redirections in the past to attack clients of sites all the time. It's
highly trivial to point to a site with a metasploit browser bug patiently
waiting and amass quite a large number of sessions in a short period of
time should your spam campaign be efficient and actually draw users to the
vulnerable site.

Just like with XSS, being able to drive clients from one site to another is
a huge security risk, not for the company, but for the clients of that
company which will quickly point fingers at the company for putting them at
risk in the first place and while I agree that the researcher shouldn't get
paid the full 500 bucks some sort of compensation for keeping Google's ass
out of the fire should be presented to the researcher; even if it's just a
friggen $100 Adwords coupon to help the researcher drive traffic to their
site at the very least.

In the end, until someone leverages one of these vulnerabilities in a large
company and pisses off a lot of clients and causes the media to go after
the company, I don't see many product vendors or large websites giving two
shits about vulnerabilities such as this which is both sad and a fact of
life.

Cheers,
connection
HackTalk Security - Security From The Underground



On Thu, Dec 8, 2011 at 12:15 AM, Michal Zalewski <lcamtuf () coredump cx>wrote:

_Open_ URL redirectors are trivially prevented by any vaguely sentient
web developer as URL redirectors have NO legitimate use from outside
one's own site so should ALWAYS be implemented with Referer checking

There are decent solutions to lock down some classes of open
redirectors (and replace others with direct linking), but "Referer"
checking isn't one of them. It has several subtle problems that render
it largely useless in real-world apps.

There are also some classes of redirection / content proxying problems
that you can't quite eliminate until you give up on offering certain
functionality to users (e.g. page translation, cached document views,
embeddable <iframe> gadgets) - and that's actually an interesting
conceptual struggle.

Apparently Google's web developers are so stubbornly unable to absorb
this simple notion that it has become company policy that officially
Google does not care about open redirectors:


http://www.google.com/about/corporate/company/rewardprogram.html#url-redirection

I actually wrote that bit, and as far as I remember, it's not a
half-assed attempt to justify incompetence ;-)

We have a vulnerability reward program, and it's just about not paying
$500 for reports of that vulnerability - along with not paying for
many other minimal-risk problems such as path disclosure.

/mz

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_______________________________________________
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Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/

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