alphalist Blog

How to Secure your App


Securing apps is vitally important. Your users are trusting you with their data and transactions and you can’t afford to betray that trust. Worst yet, you yourself can’t go down due to malicious actors. You need to make sure your process secures your app from the frontend to the backend and everything in between.

Few recognise the importance of app security more than Andreas Schranzhofer, the CTO of Scalable Capital. Scalable Capital is a Neo-Broker and robo-advisor based in Munich with over 250 million in funding. Scalable Capital is responsible for the security of a system with great financial implications and Andreas uses his  highly ‘hardware- near’ background in electrical engineering, digital signal processing, and embedded systems to ensure app security. 

He shared with us on the alphalist podcast how to secure an app and this is what we learnt:

Table of Contents

Audit everything

Know all the interfaces, all the access vectors, tools, people involved. Using that create an inventory and go through each item one by one and analyse all possible attack vectors in-house, external, etc. When you research every single of those interfaces, let your team know that you're doing that right. For Scalable Capital, there are a lot of layers and multiple complex systems that come together to create an interactive interface for the client. When they conduct an inventory, they go through each part: the app, the API, the backend, the identification layer, the authorisation layer, the connectivity to a market data service, the connectivity to the market maker or a bank. The company ensures that as these interfaces constantly communicate with each other, they ID each other and make sure that only the necessary amount of information flows through those interfaces. The entire system has to be up to date and constantly checked regarding exposure to the internet, vulnerabilities, scams, and attacks..

Securing the Device: Identity Management and Protocols

The device is the weakest link. You have the least control over it. You can’t know if the app was installed correctly if it is on a jailbroken device if the OS is up to date etc. In case the device is compromised or stolen, make sure username/password credentials are not stored on the device. (Scalable Capital has an option for users to store that data locally yet only if they have a secure place). Using SSL pinning also reduces the risk of Man-in-the-Middle Attacks. You can try to educate the user on security best practices but it also emphasizes the need for identity checks and MFA. 

Be Data Frugal with APIs.

Every bit of data exposed at an endpoint needs to be there for a reason. You don’t want someone using that data for anything else. (Andreas mentions how someone used information available on Amazon to trick the Apple support into resetting an ID). You can try obfuscate as much as you want, but at the end of the day, obfuscation is not security. (especially if not done properly, see point 3). Andreas doesn’t see much point in hiding the API. It is public-facing, people need to know how to onboard the app and understand what the app is doing and what kind of calls the app is sending to what endpoint. This is why Andreas just focuses on making sure it's a secure connection making secure communication to a controlled setup while exposing as little as possible in the API.

You Need Both Security and Obfuscation

There are many ways to secure HTTP communication and prevent Man in the Middle Attacks and make sure you are talking to the right endpoint. There is SSL pinning and other methodologies. It's a very established and value researched environment which makes it very secure. It is also a well-known and understood protocol. This also increases the risk so you need to obfuscate and also know which protocol you are using and why. It's very hard to prevent someone from sniffing network traffic using Charles Proxy and it's also difficult to prevent someone from downloading the APK (if its an Android app), disabling certificate pinning (or changing to the desired certificate), and compiling it again and there you have a jailbroken device. (Even jailbreak detection can be skipped by manipulating the execution of the application at run time). By having tight security protocols, API Data frugality, and obfuscation in place, you create a much more secure system. 

How to Prevent Supply Chain Attacks

Supply chain attacks appear in the news frequently, whether it is the SolarWinds or the Kyesa attack that took down half the supermarkets in Sweden. The best way to deal with it is to be aware of the need to assess vulnerabilities of your vendors, your libraries, and your third-party integrations and applications that you use in the context that might have access, or might be able to have access to your system. This also includes the dependencies used in GitHub. You need to have a way that when these vulnerabilities do come up, they come to your attention. Because often, as in the case of a vendor attack, you nor your vendor knows until you are locked out!

Storage Solutions: Prepare to Remediate in case of Ransomware Attack

You need to have multiple layers in protection in place anyway. What is your first layer? Second layer? Etc.  It goes without saying that you need to have a good backup strategy. A good backup strategy entails: - Up-to-Date Backups. You should be able to restore data from 15 minutes before, not months ago. - Be able to Recover in Timely Manner.  - Backup Segregated from System. This means different access vectors, third-party integrations, and encryption possibilities. - Weigh Pros and Cons of Using a Backup Service.  If using a backup service, make sure they aren’t vulnerable to the same attack vector. 

The Software Development Life Cycle: Include Coach Reviews, Porter Requests, And Checklists. 

Security needs to be on everyone's mind throughout the development cycle - not just for those on the cyber specialists. This will help raise awareness about security and ensure security has been scrutinised throughout.  

Use Tools To Identify Possible Vulnerabilities  

Automated checks using tools should be a continuous part of the CI/CD system. Some tools provide static code analysis as well as tools offered by cloud providers to detect vulnerabilities in both dependencies and images. The information generated by these tools should be constantly checked and reported to the right teams. 

Utilise External Audits 

It is valuable when an external party reviews the code infrastructure and conducts pen-tests. Just being from outside the organisation allows for a different viewpoint and also background and experiences. The yearly pen-test is partially automated, but also quite manual in its attempt to break the system. Frequent system audits (conducted externally) also make sure there is no regression. Sometimes just getting this external assistance is a huge help as, especially in small companies, the CTO is bogged down in so many other areas, having someone with more headspace conduct these audits on their behalf is helpful

Have an Ear to the Dark Side. 

It is helpful that someone aware of what is being discussed in the hacker community reviews your code. 

In this podcast, Andreas shared with us the intricacies of running a highly secure FinTech app in a regulated environment and shared tips on how all of us can secure our apps as well. He highlights the need for a multi-pronged security approach that incorporates data frugal APIs, SSL Pinning, HTTP Protocols, and obfuscation. He shared with us what proactive steps need to be taken to avoid supply chain attacks and reminds us of the importance of a good storage strategy. Andreas also tells us how he uses external audits, reviews, tests, and tools to keep his security solid and why you should too.

Andreas Schranzhofer

Andreas Schranzhofer

CTO @ Scalable Capital

Andreas Schranzhofer, as the CTO of Scalable Capital, a leading fintech company, exemplifies a blend of technical prowess and strategic foresight. In this role, he leverages his extensive experience in mobile platform management, particularly in the banking and e-commerce sectors, to drive innovation and technological excellence. His tenure at GetYourGuide, where he led the mobile engineering team, and at Avaloq Evolution AG, overseeing mobile and web banking platforms, has equipped him with unique insights into creating user-centric, secure financial technology solutions. Holding a Master's from Graz University of Technology and a PhD in Embedded Real Time Systems from ETH Zurich, Andreas combines academic rigor with practical know-how to lead Scalable Capital's tech initiatives, focusing on scalability, security, and user experience in the dynamic world of fintech.