AOL/AOL Instant Messenger Vulnerability

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Author: Robert Lyttle (robert@sub-seven.com)
Contributors: r0cky
Release Date: 02.24.02 - 2:00 AM

Disclaimer:
http://www.sub-seven.com and/or Robert Lyttle is not responsible for the misuse of the following info
rmation. 

The below was executed against business associates with their express permission as proof of concept.
 

History:
This is the second significant public release of a hole within AOL's software, making it the 4th sign
ificant hole discovered in AOL
 software since Jan 1, 2002. (w00w00, this one, and two other private vulnerabilities) In 1999, 2000,
 and 2001 there were related
 vulnerabilities against AOL Instant Messenger. 

Summary:
It is possible to retrieve the password of AOL Instant Messenger screen names through the http://free
.aol.com, http://www.aol.com
 and http://www.aim.com websites. This then leading to possible gain of other accounts such as FTP, e
-mail, and so on.

Susceptible to retrieving current password:
AOL Instant Messenger screen names that are registered to the same @aol.com address, but those that n
o longer exist in AOL's system
 (Usually 6 months after cancellation/termination of account.) Example: We have an AOL Instant Messen
ger screen name "hi mom" that
 is registered under the e-mail hi mom@aol.com - and since the hi mom@aol.com account is no longer in
 AOL's system, it is vulnerable.
 

Susceptible to take-over, but without current password:
AOL Instant Messenger screen names that are not currently in AOL's system. Social Engineering require
d. 

How:
-Visit http://free.aol.com

-At the first page enter in any information you desire. (Remember this information if you plan on soc
ial engineering your way in later.)
 Now press continue.

-On the next page you will be asked for a screen name and password. Enter in an AOL Instant Messenger
 screen name and password that
 you own, that is NOT in AOL's system - Check the check box that says "Check here to use your AI
M name on AOL" Now press continue.

-On the next page you will be asked for billing information and a new browser window will pop up. Cli
ck the "I Agree" button in the
 new browser window, it should close. Go back to the initial browser window and press the "Cance
l" link on the bottom left hand corner.

-On the next page you will be brought to a new screen that talks about Joining AOL without a credit c
ard. Now press continue.

The next 2 pages will be for verification -- Keep pressing "Continue" on the next 2 pages u
ntil you get to the page that asks for
 another screen name and password.

If you've done this correctly you will be greeted with "Sorry, <thename> is taken" th
en asked to enter another screen name and password
 as stated before. This is where you enter the screen name that you would like to retrieve the passwo
rd from. (If you enter a screen
 name that is on AOL already, you will get error saying that it is already taken.) Other errors might
 occur when trying certain screen
 names, simply press the back button and try again.

So, say we enter "S7S Robert" and for the password field you would enter any password (DONT
 FORGET IT, this will be used in the following
 steps) Press the continue button and if the name was vulnerable you will be taken to a new page and 
greeted with "Welcome to America
 Online! Congratulations S7S Robert!" Now we have access to login to the http://www.aol.com AOLA
nywhere service with the account that
 was just created. 

-Now to retrieve the current password of S7S Robert, we visit http://www.aim.com and use the Lost Pas
sword feature found under Help.
 Enter in the screen name of the password to be retrieved and press Submit.

-Visit http://www.aol.com to use AOLAnywhere and login to the account using the password you chose be
fore. You should have an e-mail
 in there from AOL with the password to the screen name. 

If you didn't receive an e-mail from the Lost Password feature, this means that the AOL Instant Messe
nger screen name was not registered
 under the @aol.com address. 

>From here an attacker could change the password to the AOL Instant Messenger screen name and also
 try the same password against the
 victims other accounts.(FTP, SSH, etc)

Testing:
To test this simply register an AOL Instant Messenger name at http://www.aim.com and when it asks for
 the e-mail address to use, make
 it the same as the screen name and append @aol.com. For instance, if I want to test with "S7S R
obert" I would enter the email address
 S7S Robert@aol.com as well. Once you've done that, you can use the above directions and see that you
 do not need the password used
 in the screen name registration process to retrieve it.

Solution:
I've e-mailed AOL multiple times before this advisory and have yet to receive a reply, so hopefully t
hey are working on it. In the
 mean time, just make sure your AOL Instant Messenger screen name's email address isn't registered to
 its old @aol.com address.

- Robert Lyttle
- http://www.sub-seven.com

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