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Re: Privat24 (Facebook version) bypass of static password for accounts of PrivatBank (Ukraine, Russia and CIS)
From: Shreyas Zare <shreyas () secfence com>
Date: Mon, 11 Oct 2010 22:28:43 +0530

LOL. It must be quite convenient to use banking alongside FarmVille.

Shreyas Zare

Sr. Information Security Researcher
Secfence Technologies
www.secfence.com


On Mon, Oct 11, 2010 at 3:57 AM, Andriy Tereshchenko <tag () 24 odessa ua>wrote:

1) Affected Service

* Privat24 application in Facebook created by PrivatBank, Ukraine

2) Severity

Rating: Moderate (need user actions or access to mobile phone)
Impact: Exposure of sensitive financial information
          and unauthorized payment transactions
Where: Remote (man in the middle), Local (removed authentication factor)

3) Vendor's Description of Service

"Privat24 application in Facebook allows to view bank statement recent
transactions on all your PrivatBank cards and account, refill mobile
phones balance. More services to be added in future."

Product Description Link:
http://privatblog.com.ua/?p=269

Actual Product Link:
http://apps.facebook.com/pb_transactions/

4) Description of Vulnerability

During registration process Facebook application ask for one-time-password
from
SMS message sent to mobile phone of registered Privat24 user.

Once user name supplied proper OTP from SMS - his Facebook account ID is
linked
to ID of PrivatBank client.

Vulnerabilities are:
1. SMS messages are not tagged in any way that they are from
  Privat24 (Facebook) system and no risks are described to client on
  disclosure of this OTP.

2. Secondary (mandatory) factor currently used on original
non-Facebook Privat24
  system ( http://privat24.ua ) is not used in this version of
application.

3. Once linking/authorization process is done - no future SMS codes or
passwords
  are needed to access application others that Facebook account
login/password.

4. Client has no control on which Facebook accounts are linked to his
  financial information.


Exploitation scenario:

Attacker create fake Facebook accounts and link them to ID of Privat
client.
In order to link attacker need short-term access to the mobile phone
(in order to receive SMS code)
or setup fake website to ask for code from SMS  (ex. eurovoice.tv SMS
best-song
voting process).

After linking - attacker can access balances and statement on last
transactions
from all accounts of PrivatBank client.
As well attacker can make small (tested are ~10 UAH) payments without any
SMS passwords.

5) Solution

a) SMS messages from Privat24 (Facebook) system should be tagged properly
in order to allow users clearly identify service and website URL of SMS
origin.

b) SMS codes should be requested on each login to Privat24 (Facebook)
  application (at least once per day) or SMS notification be sent on login.

c) Static (existing) password factor should be used in order to link
Facebook
  account to client ID or visit to ATM for extra password is
acceptable solution.

 Temporary solutions for current users offered by Rakaev Rostislav
 from bank support:

Option 1: Protect your mobile phone using PIN/password from usage by
         wife/husband or co-workers.  Never give it to unknown people.

Option 2: Blacklist own phone-number for usage in PrivatBank Facebook
         applications by contacting 0 800 500 003 (for Ukraine)
         or online-chat support.

6) Timeline

Postal mail letter addressed to author by PrivatBank from 03.05.2010
No. 30.1.0/2-100412/1849 describe intentions of PrivatBank to restore extra
login factor (static password).

Phone call from bank Security Department (Dnepropetrovsk) on 07.10.2010
with apology on inability to address issues due to conflict of interests
with
Electronic Business Department.  Insecurity accepted as trade-off.

7)  Credits

Discovered by client of PrivatBank.

8) About

The Commercial bank PrivatBank (Ukraine) was founded in 1992. Its
services are used by more than 23% population of Ukraine population.
PrivatBank currently serves 420 thousand corporate clients and small
businesses, and over 13 million individual accounts.

Moscomprivatbank Joint Stock Co. is subsidiary of PrivatBank.
It has about 1.5 million credit cards issued.

Privat24 is online-banking system used by more 1 million clients in
Ukraine,
Russia and CIS.

9) Links

Privat24 (Facebook version)
http://apps.facebook.com/pb_transactions/

Vendor announcement of service
http://privatblog.com.ua/?p=269

Existing Privat24 system
http://privat24.ua



--
Andriy G. Tereshchenko
Odessa, Ukraine
+380683777768

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

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