How to maintain validity of user credentials?

Question

In an example scenario consider that;

1. I am a customer of organisation and I have two separate accounts with two different departments X and Y.
2. I can login in to each department's website by using user id and password that is unique for each department.
3. To update my personal details in any deprtment, I have to call this service provider and use a PIN code (sent to me earlier, through a secure channel). They have separate teams for each department so X doesn't know about Y.
4. Although I have separate profiles/accounts for each department, note that the PIN code is the same whether I call department X or Y.
5. In this scenario both departments have different levels of allowed actions associated with PIN code. For example I am not allowed to change my address when calling department X with this PIN because its considered lower level authentication factor. However if I want to do the same in department Y, I may be allowed to so because it is considered as higher level authentication factor.

Now the problems I see in this scheme are:

1. A fraudster who has somehow skimmed my basic details, like Name, DOB etc can call department X ask for this PIN (which ironically can be given over the phone) because its considered to allow only low risk operations. Consequently once the fraudster gets this PIN, he can then call into department Y and perform changes without being challenged because its allows high risk operations.
2. Second problem is that same PIN number is used for two different departments.

Now my question is that consider I can't have separate PIN codes's and they can't have same level of authentication associated to them for X and Y.

1. What can the organization do to stop fraudulent use of PIN code across different departments

2. Is there a way to maintain the validity of credentials by associating change of scope (department which resets/re-issues PIN code) and extent (change of personal information) to PIN code. So that misuse can be stopped.

Answer 1

This organisation should have a specific landing point for customers to receive/verify/modify their PIN code, which does not depend on departments, and department staff should be trained to not give this information just as they would not give other sensitive personal information.

The reason is you can't ask departments to reason about the sensitivity of the PIN code themselves if they don't know what others are doing (or will be doing in the future) with this PIN. Also, it'd be much costlier to setup an organisational or technological mechanism for departments to check the sensitivity of the PIN in situ so they can decide whether to disclose it over the phone or not. It's easier to have a separate team for handling the PIN so a unique policy can be created, updated and enforced.

Note that at this point it makes a lot of sense to have a cross-department account management system with some amount of information reuse. You already need this for such a PIN (though I must say the primary issue probably is that the PIN exists in the first place).