Thick client (desktop) applications carry risk a web test never sees: secrets baked into the binary, data cached insecurely on disk, and trust placed in a client an attacker fully controls. This is dedicated thick client penetration testing across the binary, the local system and the back-end it talks to.
We treat the installed application as fully attacker-controlled: reverse-engineering it for hardcoded secrets and logic, inspecting how it stores data and loads libraries, and intercepting its traffic to test the server it trusts. Client-side controls are assumed bypassable and tested as such.
The core thick-client mistake is trusting the client — enforcing licensing, validation or authorization in software the user owns and can patch. That trust is exactly what we break, then follow the trail to the back-end.
What we test
Binary and reverse-engineering analysis
Local data storage and configuration security
Traffic interception and TLS validation
DLL hijacking and library loading
Inter-process communication (IPC) security
Privilege escalation and installation flaws
Common vulnerabilities we uncover
Hardcoded credentials and secrets in binaries
Insecure local storage of sensitive data
Weak or missing transport encryption
DLL hijacking and injection
Insecure IPC and named-pipe abuse
Client-side trust and tampering flaws
Our methodology
Scoping & rules of engagement. We agree objectives, targets and boundaries for your thick client application penetration testing, so testing is safe, authorized and focused on what matters to your business.
Reconnaissance & mapping. We enumerate the full attack surface in scope, building a complete picture before any exploitation begins.
Manual exploitation. Our senior testers chain vulnerabilities by hand — going far beyond automated scanners — to prove real, demonstrable impact.
Analysis & reporting. Every finding is triaged, risk-rated with CVSS and written up with a copy-paste reproduction and clear remediation.
Remediation support & free retest. We support your team through the fixes and retest the remediated issues to confirm they are genuinely closed.
Tools & techniques
Our approach spans three layers: the binary (reverse engineering, hardcoded secrets, anti-tamper), the local system (storage, registry, DLL loading, IPC, privilege), and the network (intercepting and testing the back-end API the client trusts). Findings are proven, not theorised.
Because the server behind a thick client is often the bigger prize, this connects to our API penetration testing and secure code review, and complements full web application penetration testing.
When you need this engagement
You ship a Windows, macOS or Linux desktop application
Your client talks to APIs or databases directly
You handle licensing, secrets or sensitive local data
You are in finance, trading or industrial software
You need more than a web-only assessment
What you receive
Executive and technical report with evidence
Binary, storage and traffic findings prioritised
Reproduction and remediation guidance
Back-end API findings where in scope
Attestation letter where required
Complimentary retest after fixes
What’s included in your report
Every thick client application penetration testing engagement concludes with a comprehensive, board-ready report and a working session to walk your team through it. Your report includes:
An executive summary with overall risk posture for non-technical stakeholders
Detailed technical findings, each with a step-by-step, copy-paste reproduction
CVSS v3.1 severity ratings and business-impact context for every issue
Prioritized, actionable remediation guidance your engineers can apply directly
A complimentary retest to confirm fixes and update finding status
A formal attestation letter for customers, auditors and compliance programs
Standards & frameworks
OWASP (adapted for thick clients)CWE Top 25NIST SP 800-115Platform hardening guidance
Outcomes you can expect
After your thick client application penetration testing, you will have clear, evidence-based visibility into your real security risk — not a scanner’s guesswork. You will know exactly which weaknesses an attacker could exploit, what the business impact would be, and the precise steps to fix them in priority order. Teams use our findings to close critical gaps, satisfy customer and regulator security requirements, and demonstrate due diligence to their board. With a complimentary retest included, you also get documented proof that the issues are genuinely resolved.
Engagement details & logistics
Every thick client application penetration testing starts with a short, no-obligation scoping call to understand your goals, environment and constraints, followed by a fixed-price proposal and a clear statement of work. Most engagements are delivered fully remotely, with on-site work arranged where it genuinely adds value. Throughout testing we maintain an agreed communication cadence and escalate any critical, high-impact finding to you immediately rather than waiting for the final report. All work is performed under a signed NDA with strict data-handling controls, using safe, non-disruptive techniques and carefully coordinated rules of engagement to protect your production systems. On completion you receive your report and a walkthrough session, followed by a complimentary retest once your fixes are in place. Typical engagements are booked one to three weeks in advance, and urgent or pre-deadline testing can often be accommodated — just ask at hi@agentoffense.com.
Why organizations choose AgentOffense
Our thick client application penetration testing is delivered by senior offensive-security engineers who test the way real attackers do — manually, creatively and with a relentless focus on proving genuine, demonstrable impact. Here is what sets our engagements apart:
Manual, exploit-driven testing that chains vulnerabilities the way a real attacker would, going far beyond what automated scanners can find.
Reproducible proof for every finding, with copy-paste reproduction steps your engineers can follow and independently verify.
Honest severity calibration so you invest in fixing what genuinely matters and avoid wasting effort on false positives and noise.
Clear, business-focused reporting that speaks to engineers and executives alike, tying every issue to real-world impact.
A complimentary retest included, so you get documented proof that your fixes actually close the attack path.
Responsible, collaborative delivery with a named point of contact and secure handling of all data throughout the engagement.
Explore related services
Thick Client Application Penetration Testing is frequently scoped alongside our other offensive-security services for broader coverage. Explore related engagements that complement it:
Web Application Penetration Testing — Manual web application penetration testing against the OWASP Top 10 and business-logic flaws. Exploit-driven testing with…
API Penetration Testing — REST and GraphQL API penetration testing against the OWASP API Top 10 — BOLA, BFLA, mass…
Secure Code Review — Manual secure code review backed by SAST — data-flow and taint analysis, secrets detection and insecure-pattern…
How much does Thick Client Application Penetration Testing cost?
Every thick client application penetration testing is scoped and priced individually, so you pay for exactly the coverage you need — with no hidden extras. After a short, no-obligation scoping call we send a fixed-price quote, usually within one business day, with clear deliverables, a firm timeline and a complimentary retest included. The price of your thick client application penetration testing depends on the size and complexity of the target and the depth of testing required, so you always know the cost up front before any work begins.
