Flaw in UIDAI’s SMS service lets anyone with your Aadhaar number trace your bank info

The flaw could see more sophisticated and targeted social engineering attacks, researchers say.

The flaw resides in the USSD service that UIDAI publicly shared in December last year. (Vipin Kumar/Hindustan Times)

In light of media reports about access to a specialised Aadhaar website being sold for as little as ₹500, an SMS flaw in UIDAI's service has become apparent that allows anyone who has your Aadhaar number to figure out your bank details.

The flaw resides in a USSD service that UIDAI publicly shared in December last year. First reported by Gadgets.NDTV, the service allows anyone to check if their bank account has been linked to their Aadhaar number, as has been mandated by the authority.

1. Dial *99*99*1# from your phone.

2. A dialogue box is prompted on the screen, which asks the user to enter their Aadhaar number.

3. Confirm whether the Aadhaar number you have entered is correct.

4. At this point, the service states whether any bank account has been linked to the provided Aadhaar number. If a bank account is linked, the name of the bank account is displayed.

While that's a useful and quick service, a flaw in it has been reported by users this week. According to researchers, the USSD service can be fed with Aadhaar number of other people and it fetches their bank details. Put simply, if you entered the Aadhaar number of any random person, you can find with which bank they have an account.

@UIDAI Secure this service with mobile OTP verification ASAP. Otherwise it's very unsafe and foolish. https://t.co/XOnhnaF1bm

— Jha Avinash (@avin_asansol) January 9, 2018

Apparently, anybody can check the bank account linked to any #Aadhaar number. What an idea. https://t.co/jhIZ2gO8xN

— manoj nayak (@manoj1802) January 9, 2018

Not even only urs, u can check anyone's bank details, if u know his/her Aadhaar no.
By dialing *99*99*1# , it ask for aadhaar no.
No OTP required, no registered mobile no. required.
This how our data have been secured!!! 😂😂
Detailed article published in economic times. https://t.co/TqqMNhG2ON

— Mannick Shah (@Aapka_Shah) January 8, 2018

The problem, security researchers say, there is no authentication system in place to verify if the person who has requested the bank information is the rightful owner of the associated Aadhaar card. For instance, UIDAI could have implemented an SMS-based OTP service. This would have alerted the rightful owner of the Aadhaar card that their account information has been requested.

Knowing such information could come in handy to hackers, marketers and spammers, researchers say. In the recent months, we have witnessed Aadhaar details of people surfacing online on a few government websites. Keeping this in mind, a hacker can "now extract your bank name too along with all your other private information including mobile number, address, etc," Ankush Johar, Director at security firm Infosec Ventures said.

"In such a scenario, it would be extremely easy to socially engineer victims over call or email as the attacker will have targeted information about his victim. This is called Spear Phishing and can be extremely dangerous," he added.

In such attacks, a person gives the victim a phone call and pretends to be from a certain bank. They now have your Aadhaar number with them as well, which could potentially lend them more credibility in gaining the trust of victims. This is just one example, there could be a myriad of ways vicious minds could make use of such sensitive information.