Credit card statement disclosure vulnerability in Viseca's eXpense portal
As a security company we try to use services that are solid, trustworthy and secure and therefore we do our due diligence if we find the time for it. Checking products for IT security issues in a non-intrusive way is a part of that. You can call it supply chain security if you like.
To avoid scanning credit card paper statements sent by snail mail every month, Pentagrid was looking for an option to receive them electronically. For our bank though, the only option was to sign up for Viseca's eXpense platform, which allows access to business credit card statements in PDF format. However, uppon login into the portal for the first time, our experienced analyst's gut feeling told us something is not right. For example, the second-factor authentication when doing a login on the eXpense platform was simply typing the last four digits of our telephone number. And that's definitely not state-of-the-art security.
We decided to have a quick look. Our experience in web application security analysis told us that the download function for PDF statements was a good candidate to have a look at. We've seen this kind of functionality fail in many applications before. You may guess, what happened.