full-disclosure - Re: JavaScript exploits via source code disclosure

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Date: Thu, 06 May 2010 18:39:52 +0200
From: PsychoBilly <zpamh0l3@...il.com>
To: Marsh Ray <marsh@...endedsubset.com>
Cc: full-disclosure@...ts.grok.org.uk
Subject: Re: JavaScript exploits via source code disclosure

************************  Cluster #[[   Marsh Ray   ]] possibly emitted, @Time [[   06/05/2010 17:42   ]] The Following #String  **********************
>
> Adversary simply modifies your page in transit to not use the
> 'jcryption', or to leak him a copy of the session key.

Tss Tss, I'm not stating client-side javascript is secure / can be obfuscated.
Just provided a hint

1 - let's say it's a customer login area
Case 1: legitimate user > usr+pw are transmitted encrypted, then ajax get/post calls are then still encrypted + each request is followed by a valid encrypted client session ID.
Case 2: Opponent > trying to exploit login > the pb here is getting thru / not JS related // trying to exploit the ass > does not know any valid encrypted session ID > server side can drop this with minimum ressource.
- not using encryption: server-side script drops connection ( as it has the duty to decrypt posts )
- leak a session key: ok, fine the opponent does have a unique ID that leads him to a login area.

2 - There's no login: it's an API // forget js because, yes, all the logic is in the oponent hands & executed on opponent machine ( so source encryption is useless ).

3- nobody can guess where/what is open on target machine, a proxy is giving one port/valid encrypted ID or just drops connection.

>
> This kind of thing will only deter people who don't know any better or
> people with little motivation to care about your data anyway. Using it
> is only an admission that you are either incompetent or don't have
> anything worth the slightest effort to steal.
>
> - Marsh

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