Date: Mon, 11 Oct 2010 22:28:43 +0530
From: Shreyas Zare <shreyas@...fence.com>
To: Andriy Tereshchenko <tag@...odessa.ua>
Cc: Full Disclosure <full-disclosure@...ts.grok.org.uk>,
	BugTraq <bugtraq@...urityfocus.com>
Subject: Re: Privat24 (Facebook version) bypass of static
 password for accounts of PrivatBank (Ukraine, Russia and CIS)

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@...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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