What’s really happening inside your desktop app?
Desktop applications tend to do more than they let on. Behind the interface, a thick client can hold business logic, credentials, tokens, configuration files, and cached data right there on the user’s machine. It often talks directly to databases, APIs, and internal systems too.
That’s a lot of surface area for something to go wrong. If there’s a weakness anywhere in that chain, an attacker might be able to pull data off the endpoint, misuse an API, or reach into your backend systems. A Thick Client Security Assessment is how we find those weaknesses first.
We look at the application itself, its local components, how it talks to your systems, its authentication, its APIs, and the backend services behind it. Then we help you understand what’s actually risky and what to fix.
What is a Thick Client Security Assessment?
It’s a security review built specifically for desktop applications, the kind that do a lot of processing locally or store data right on the user’s computer.
Unlike a browser-based app, a thick client can contain business logic, config files, credentials, tokens, and libraries sitting on the endpoint itself, plus direct connections to databases, APIs, web services, or internal infrastructure. So we look at both the application and everything it talks to.
Depending on your app, that can include:
- The application’s binaries and executable files
- Local data storage
- Authentication and session handling
- Configuration
- APIs and web services
- Database communication
- Network communication
- Encryption and cryptographic controls
- Access control
- Business logic
- Third-party libraries and components
- Sensitive information sitting on endpoints
Why it’s worth doing
A desktop app can quietly become the easiest way into your wider business systems. A weakness in the client might expose credentials, sensitive data, APIs, databases, or internal services that were never meant to be reachable.
Testing helps you catch problems before someone else does: sensitive information stored locally, weak authentication and access controls, insecure communication, hardcoded credentials or secrets, and outdated or vulnerable components. It also shows your team how the application actually behaves outside normal, everyday use, which is usually where the interesting problems live.
What we look at
Architecture. We start by understanding how the pieces fit together: the desktop app, APIs, databases, authentication systems, internal services, and any third-party components. That tells us where the trust boundaries are and where to look harder.
Authentication. We check whether users are properly verified before they get access. That covers login mechanisms, password handling, multi-factor authentication, session management, token handling, ways authentication might be bypassed, account lockout, and how credentials are stored.
Authorisation and access control. Being authenticated tells you who someone is. It doesn’t tell you what they should be allowed to do. We look for privilege escalation, ways to bypass roles, weak access controls, insecure direct object references, and unauthorised functionality, including anything enforced only on the client side.
Local data storage. Thick clients tend to leave things behind on the device: configuration files, application databases, logs, cached data, temporary files, credentials, tokens, encryption keys, and business data. We check whether any of that is exposed or can be tampered with.
Binary and code analysis. Application binaries, libraries, and configuration files can reveal more than they should. We use static and dynamic analysis to understand how the app behaves and check whether sensitive information, security logic, credentials, or API keys are unnecessarily exposed.
Network communication. Most thick clients talk to remote servers, APIs, databases, or internal services. We check whether that traffic is properly protected and whether it could be intercepted, modified, or misused. That includes TLS configuration, certificate validation, API communication, protocols, sensitive data in transit, insecure endpoints, and whether requests and responses can be manipulated.
APIs and backend. If your app leans on APIs or backend services, we check whether the client can be tricked into doing things it shouldn’t. That covers authentication, authorisation, input validation, session handling, and business logic.
Business logic. Not every problem is a technical bug. Sometimes it’s how a process was designed. We test whether users can skip required steps, change transaction values, reach restricted functions, repeat sensitive actions, get around business rules, or manipulate requests.
How we work
1. Scope and planning. We start by understanding your application, environment, user roles, supported operating systems, backend services, and what you want tested. We agree the scope before anything starts.
2. Application discovery. We look at the app’s architecture, components, communication methods, and dependencies to understand how it actually works, so we know where to focus.
3. Static analysis. We review the application files, binaries, configuration files, and libraries for exposed information and potential weaknesses.
4. Dynamic testing. We run the application and see how it behaves under different conditions, examining requests, responses, authentication flows, local storage, and application functions along the way.
5. Validation. We confirm which findings are genuinely exploitable, which cuts down false positives and gives you a clear picture of the real risk.
6. Risk prioritisation. We weigh exploitability, the assets affected, business impact, and how sensitive the exposed information is, so you know what to tackle first.
7. Reporting. You get a detailed report covering the vulnerabilities, the affected components, the evidence, the risk level, and how to fix each one.
8. Fixes and retesting. Once you’ve made changes, we can test again to confirm the issues are actually resolved.
What we test for
Depending on your application, that can include hardcoded credentials, exposed API keys, weak authentication, authentication bypass, privilege escalation, and insecure local storage. We also look at sensitive information exposure, weak encryption, poor certificate validation, insecure network communication, inadequate access controls, and client-side security controls that can be bypassed. Beyond that, we check for business logic vulnerabilities, insecure configuration, vulnerable third-party libraries, debug information exposure, reverse engineering risks, insecure update mechanisms, API security weaknesses, and exposed database connections.
Thick client vs. web application testing
Both look at application security, but the attack surface is different. A web app is generally accessed through a browser, with most of the heavy lifting happening server-side. A thick client can carry logic, files, libraries, and credentials right there on the endpoint. That’s why a thick client assessment looks at both the desktop application itself and everything it talks to.
Who needs this
Thick client testing tends to matter most for organisations building or running desktop applications in banking and financial services, healthcare, insurance, manufacturing, retail, government, and education. It’s just as relevant for enterprise software, ERP and CRM systems, internal business applications, engineering and industrial systems, and remote administration platforms.
It matters most when the application handles confidential information or connects to important backend systems, which, in practice, describes a lot of internal business software.
When to test
It’s worth doing when you’re releasing a new desktop application, planning a major update, or introducing new APIs or backend services. It’s also worth doing after a change to authentication, a change in how sensitive data is handled, or a move to new infrastructure.
Beyond that: when security requirements have changed, when a compliance review calls for testing, when vulnerabilities have shown up in related systems, or simply when an application hasn’t been looked at in a long time.
Regular testing helps you catch new risks as the application, and everything around it, keeps changing.
Why Sunvak Boreal
We don’t stop at the visible interface. Our assessment considers the desktop application, the local environment, the communication channels, the APIs, the backend services, and the security controls that all work together to support it.
That means practical testing, real vulnerability validation, risk-based findings, business impact in plain language, actionable remediation guidance, detailed reporting, and retesting once you’ve made the fixes. The goal is findings your security team and developers can actually act on.
Final thoughts
A desktop application usually has more going on than what’s visible on screen. Local files, application logic, APIs, credentials, backend connections, and communication channels can all introduce risk that never shows up in the UI.
A Thick Client Security Assessment finds those weaknesses before they turn into bigger problems. We can assess your desktop applications, identify the gaps, validate what’s genuinely exploitable, and give you practical recommendations for strengthening the application and everything around it.
FAQs
What is a Thick Client Security Assessment?
A security assessment of desktop applications and the systems they communicate with, covering authentication, local storage, application logic, network communication, APIs, and backend services.
What’s the difference between a thick client and a web application?
A thick client does more processing on the user’s device and may store components or data locally. A web application relies more on browser access and server-side processing.
Can you test Windows and other desktop applications?
Yes. We adapt the scope to the application’s operating system, architecture, technologies, and deployment environment.
Does the assessment include API testing?
Yes, when APIs are part of the architecture. We can assess authentication, authorisation, input handling, business logic, and other relevant controls.
Can you identify hardcoded credentials?
Yes. We review application files, binaries, configuration files, and related components for exposed credentials, secrets, API keys, and other sensitive information.
Do you provide a report?
Yes. You’ll get vulnerability details, affected components, evidence, risk context, and recommended remediation steps.
Can you retest after fixes?
Yes. We can confirm whether previously identified vulnerabilities have actually been addressed.
Is this useful for internal applications?
Yes. Internal applications can carry real risk, especially when they connect to sensitive databases, internal services, or privileged systems.
Secure your desktop applications with a Thick Client Security Assessment
Talk to Sunvak Boreal about your desktop applications, and find out where they need stronger protection.