An information disclosure vulnerability has been identified in Money Lover, a finance tracking application created by Finsify and available on Android, iOS, Microsoft Store, with a web interface. This vulnerability allows any authenticated user to view live transactions related to shared wallets. The information inadvertently disclosed by the app could allow a malicious actor to use the email addresses and metadata disclosed in this vulnerability, such as transaction IDs and wallet names, for further exploitation in case there are other vulnerabilities found within the application.
I use Money Lover on a daily basis, so I naturally became curious about its traffic, which led me to discover the bug. I was using the web user interface version at the time and routed the traffic through a proxy. Given that Money Lover is a finance app which has a feature that connects to actual bank APIs, I did not feel it appropriate to tamper with the traffic being sent to the server.
By default, Money Lover logs a user’s transaction into the user’s own “wallet.” However, Money Lover also offers a “Shared Wallet” where two or more users share a wallet in order to collaborate on transactions such as expense logging and monitoring, and this is where I found the problem. The shared wallet transactions disclose user information, such as the user’s email address and shared wallet name. The email address and shared wallet name can be viewed via the Web Sockets tab of the browser’s “Developer Tools.” All Money Lover users who make use of the Shared Wallet feature are affected by this issue.
Figure 1: Money Lover application
While passively observing, I browsed to the Web Sockets tab and found a few unknown email addresses. For the first few seconds, I thought that the email addresses belonged to Money Lover’s developers or the authors of some JavaScript library. That is until more emails started to come in.
Figure 2: Browsing the Web Sockets tab
A closer look revealed email addresses and wallet names in different languages from all around the globe. At this point I realized something was wrong with the app as I should not be able to view this information and I decided to contact the developer.
Figure 3: Web Sockets history tab
Figure 4: Viewing the disclosed sensitive information through a browser’s Developer Tools
Responsible Disclosure
This vulnerability was reported to Finsify as part of Trustwave SpiderLabs’ Responsible Disclosure policy. Finsify confirmed that developers monitor the email address contact@moneylover.me. After sending the proof of concept (POC) to Finsify, the company stopped responding to our email and Facebook Messenger communications.
After multiple attempts to reestablish communication with Finsify, it was decided to move forward with public disclosure to warn users about this information disclosure vulnerability.
Update
As of January 27, 2023, Trustwave SpiderLabs observed that the information disclosure vulnerability in the Web Sockets of Money Lover’s Web Interface had been fixed as we are no longer seeing any email and wallet names populate the Web Sockets messages section.
Conclusion
Overall, this bug discloses email addresses and shared wallet names of users who actively use the wallet sharing feature of Money Lover. In addition to the user email address already disclosed by this vulnerability, a malicious actor targeting users and businesses could use the metadata disclosed in this vulnerability, such as transaction IDs and wallet names, for further exploitation in case there are other vulnerabilities found within the application.
Reference
TWSL2023-003: Information Disclosure Vulnerabilities in Money Lover
