Performing Thick Client Application Penetration Test

Overview

Thick client (fat client) penetration testing assesses the security of desktop applications that run locally on user machines and communicate with backend servers. Unlike web applications, thick clients present a broader attack surface including local file storage, binary analysis, memory manipulation, DLL injection, process interception, and client-server communication. Common targets include banking applications, ERP clients (SAP GUI), trading platforms, healthcare systems, and legacy enterprise software.

When to Use

• When conducting security assessments that involve performing thick client application penetration test
• When following incident response procedures for related security events
• When performing scheduled security testing or auditing activities
• When validating security controls through hands-on testing

Prerequisites

• Application installer and valid credentials
• Windows/Linux test machine (isolated)
• Tools: dnSpy, Procmon, Process Hacker, Wireshark, Burp Suite, Echo Mirage, Fiddler, IDA Pro/Ghidra