Pre-hijacking account takeover fraud is a form of fraud that compromises accounts before they are even created. How though, can a person fall victim before their account even exists? With some initial set up, fraudsters can do exactly that by potentially using one of five recently exposed ways to perform account takeover fraud pre-hjijacking attacks.
In 2020, the Microsoft Security Response Center offered a grant to fund multiple projects targeted at improving the security of its identity systems and protocols. The first resulting publication was a recent paper written by an external, independent security researcher, Avinash Sudhodanan, in partnership with Andrew Paverd from the MRSC. Within it, they explained these methods and how they were seen possible upon 35 of the 75 popular websites and online services that they analysed. These included LinkedIn, DropBox, Instagram an WordPress, who were all later informed of their vulnerabilities after the research was complete.
How Pre-hijacking Account Takeover Fraud works
In order for unauthorized access to be considered account takeover fraud pre-hijacking, the fraudster needs to perform some sort of action prior to the account even existing upon the platform. In these reported instances of exposure, the hijacker starts by simply creating an account using the potential victim’s email address. They could, even, just guess email addresses and hope that they belong to a genuine person or even check them against free online verification services to make sure they exist.
The accounts are typically created in bulk and, to find the most success for their efforts, bad actors will target popular apps and sites where there are greater chances of a genuine customer creating an account.
Once the genuine email address owner makes their own account, a little time will be given for them to potentially add their personal details and, perhaps, store their payment credentials before one of the methods are then used to allow the perpetrator to gain access to the account and use as they choose, successfully performing an account takeover attack.
Pre-hijacking Account Takeover Fraud Methods
Classic-Federated Merge Attack
Federated identities are those services which already have customer identities stored are often used by additional websites and apps in lieu of having a customer go through the process of entering their details to sign up an sign in to their account. These are offered by Gmail, Yahoo and the like.
Some companies tend to merge these by default. Therefore, if an account is created by using a genuine gmail email address by an infiltrator, and then the genuine owner creates an account using their same gmail social login account, they will be combined into one and both the customer and fraudster will have access to it with their own independent login information.
Unexpired Session Identifier Attack
An attacker could create an account using a genuine customer’s email address but not close out their session with the service. When the owner creates their own account using the same email address, they get prompted that an account already exists and then might choose to reset their password. Although the customer would then have access to their “new” account, without the malicious session ended, the fraudster will still have access, as well.
Trojan Identifier Attack
The hijacker might create an account using a genuine patron’s email address and set up a secondary account recovery option. This could be their own email address or phone number. Once the victim attempts to create an account and reset their password upon notification of the account’s existence, the fraudster also gets a notification to reset the password. They do so and recover control of the account from the genuine user.
Unexpired Email Change Attack
Going this route, the fraudster will create an account using their target’s email address and then initiate a change of email request to an address that they own and have access to. The site will typically send a verification email to the bad actor’s email address, however, the attacker will not complete the process, saving it for later. Once the genuine customer goes through the creation and recovery process described in the previous two methods, the fraudster will complete the verification email actions and regain access to the account.
Non-Verifying IdP Attack
Simply put, an identity provider is any system entity that creates, maintains, and manages identity information for principals or authentication services within a network. If you collect such information for these purposes, which most online services do for the accounts upon their platforms, you are, in part, an identity provider. Some companies who allow for this, like with the federated identity merge, simply combine accounts sharing details.
For this method, the attacker targets apps and sites that do not verify email addresses. They will simply create an account using their victim’s email address and, when the genuine client creates their account, the merger will happen and the fraudster will have access to the later-created account.
Prevent Pre-hijacking Account Takeover Fraud
If you are attempting to register an account on a site or service that you have not previously used and are prompted that an account already exists, do not simply initiate resetting the password. If you need to create the account, use an email forwarding address that will send the messages to your main email account or a different email address all together. Report that this happened so that the platform may be made aware and look into the potential of this fraudulent activity happening within their networks.
I would also recommend that you create federated identities with secure services, but do not use them to create accounts with other services. Own both your email and their identifying social login information to avoid those potential mergers. Again, if you are a victim of a social merger, report it.
I have read of those suggesting the turning on of 2FA or MFA as soon as you change the password after getting the message that the account already exists if they are available options. However, those will not stop all of these methods from working. I would suggest doing your best to avoid them as best as possible.
Verify email address upon account creation. You should be doing this, but if you do not, watch for spikes in account creations and monitor high-velocities of email changes and secondary recovery emails and phone numbers being the same or following the same patterns across multiple accounts. Keep an ear to the ground for customer contacts aying they have not created an account but the platform is saying that they have when they try and make one.
Do not merge any accounts. If you do, do not do so automatically. This should be an additionally approved process from the verified owner(s) of both accounts if you must do it.
Expire sessions. You should not only have general security and safety expiration in place base on time and typical actions, you should also do so upon the unexpected and risky, such as two accounts being created with the same information. Force an end to all sessions on all of the accounts that share those details.
Expire password reset URLs, links, OTPs, emails and SMS pushes. Keep that window too narrow for fraudsters to attempt these methods. A genuine user is going to want to reassess their account immediately. There is no reason for these to be live for days. Not even a day. Give them an hour or two.
This article was contributed by Shawn Colpitts, Senior Fraud Investigator at Just Eat Takeaway.com