Abnormal has detected campaigns targeting our customers where malicious actors will impersonate major brands and reach out to accounting teams to ask if there are any outstanding invoices for the company they are impersonating.
Abnormal classifies these messages as “Payment Inquiries”, and while these messages may not seem like attacks, they are the precursors to Invoice and Payment Fraud. As a result, organizations should be very careful with these messages, and ideally, their email security solutions should prevent these messages from reaching the inboxes of employees.
Payment Inquiry messages are a very common way through which attackers gain the information they need to initiate successful Invoice/Payment Fraud attacks. The goal of these Payment Inquiry messages is to gain information about the payment status of invoices and subsequently redirect payment to be sent to a fraudulent bank account. These Payment Inquiries typically have the following characteristics:
Impersonation of a Known Brand
Innocuous Content
Change in Reply-to Address
Here is an example of a Payment Inquiry message that Abnormal Security has detected for one of our customers (we’ve anonymized some of the names and email addresses for privacy reasons):
Subject: [External] Invoices / Due Payments
Sender: Samsung (accountreceivables@samsung.com)
Reply-to: acountpayabledept@personalemail.com
Hi,
We want to update our record of accounting for the month ended April,2020 which is yet to be balanced and also audit our account’s opening balance for the new month, Therefore we will like to know if there is/are any outstanding payments till date. If there is, then for the record let us know how much is due and when is the invoice due date?
Due to the pandemic crisis we urge you to review all outstanding invoices with you.
stay home and stay safe.
John Smith
Before we dive into the implications of these Payment Inquiry messages, let’s discuss Invoice Fraud attacks more generally in order to understand how these Payment Inquiries fit into the strategies of attackers.
Typically, Invoice Fraud attacks are hyper targeted attacks. In these attacks, attackers hijack existing financial conversations to attempt to execute payment against fraudulent invoices or attempt to update a valid payment with fraudulent bank account details.
Invoice Fraud attacks are high-cost, high-reward attacks:
Invoice Fraud attacks often require attackers to be engaged with their targets for long periods of time. For example, Abnormal Security observed an attack while our tools were operating in passive mode that was conducted over 9 weeks. Attackers will engage in these drawn-out attacks because the financial rewards can be significant – in the case of this 9-week attack, they would have stolen more than $700k from the target had Abnormal not stopped this attack.
Attackers are able to reduce the cost of conducting Invoice Fraud attacks by leveraging Payment Inquiries as a first step. Because these attacks impersonate or spoof addresses of known brands like Samsung and Unilever, they don’t require stolen credentials to hijack conversations. This allows malicious actors to create significantly more opportunities for Invoice Fraud attacks.
Attackers do this by employing a “pray and spray” method, sending generic inquiry messages to multiple recipients, sometimes at different companies. These inquiry messages are seemingly innocuous because they’re only requesting information, and attackers only need to get a single engagement from a target with the information they’ve requested in order to initiate an attack with that information.
Attackers are able to execute exponentially more Payment inquiry attacks than targeted Invoice Fraud attacks because of its low cost.
Let’s take a look at real life examples of Payment Inquiries that Abnormal has detected in order to understand how these messages lead to attacks.
Abnormal Security has been catching numerous Payment Inquiry messages since we launched our Supply Chain protection product. Recently, we observed a coordinated Payment Inquiry message sent to various Accounts Payable team members within a single customer over the span of a few days. These messages spoofed various known brands (Samsung, Halo Electronics etc.) with the same generic request to gain information about overdue payments. Messages were identical with suspicious reply-to addresses, indicating a strategy of diverting conversation away from the spoofed inbox, and a hope that employees would provide them with information about outstanding payments.
We have also been observing identical Payment Inquiry messages sent to multiple customers for each brand that is impersonated, indicating that the hypothesis of the spray and pray technique is true.
Here’s the example of the email again:
Hi,
We want to update our record of accounting for the month ended April,2020 which is yet to be balanced and also audit our account’s opening balance for the new month, Therefore we will like to know if there is/are any outstanding payments till date. If there is, then for the record let us know how much is due and when is the invoice due date?
Due to the pandemic crisis we urge you to review all outstanding invoices with you.
stay home and stay safe.
John Smith
Note that this email doesn’t (yet) request anything that seems like an attack. However, this is still a dangerous message for employees to engage with, because it can lead to an attack. Here’s how the attack could play out:
Thus, these seemingly innocuous messages have the potential to lead to large financial losses.
Abnormal Security doesn’t just protect our customers from Fraud and Billing Account Update attacks. We also protect our customers from Payment Inquiry messages that lead to those attacks.
Our ABX technology uses impersonation signals and content signals to identify and remediate Payment Inquiry messages from your environment.
These can be observed in VendorBase, our global, federated database on vendor and customer behaviors:
Read more about VendorBase, and schedule time with an Abnormal Email Security Specialist for a one-on-one product demo.