Thick Client Application Security Audit

 

A Thick Client Application Security Audit is a detailed review of a desktop or heavy client application (often installed locally on user machines) to identify security vulnerabilities. These applications usually communicate with backend servers, and auditing them requires both binary analysis and network traffic inspection.

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🖥️ Thick Client Application Security Audit – Checklist Table

#	Audit Category	Control / Test Description	Evidence/Output
1	Architecture Review	Understand the app's structure, components, and communication flows	Architecture diagram, app documentation
2	Binary Analysis (Static)	Analyze executable for embedded credentials, APIs, sensitive data	Reverse engineering findings (using tools like Ghidra, IDA)
3	Code Obfuscation Check	Determine if code is obfuscated to prevent reverse engineering	Decompilation output, obfuscation status
4	Local Data Storage	Review where/how data is stored (file system, registry, local DB)	Evidence of PII/passwords stored in plain text
5	Configuration File Security	Check config files for hardcoded secrets or insecure permissions	Sample insecure config.xml, .ini, or .json
6	Authentication & Session	Assess login methods, session tokens, password storage	Captured login flow, insecure token storage
7	Authorization Bypass	Test for privilege escalation and access control flaws	Use of debugger or tampering tools to elevate roles
8	Input Validation	Test input fields for SQLi, command injection, buffer overflow	Injection payload results, fuzzing reports
9	Cryptographic Practices	Review implementation of encryption/decryption in storage & transit	Weak cipher use, static keys found in binaries
10	Logging & Debug Artifacts	Check for excessive logging, sensitive info in logs or debug messages	Log file review, debug window screenshots
11	Network Communication Security	Analyze communication between client and server (encryption, authentication)	Packet capture (e.g., Wireshark), SSL handshake review
12	Proxy and MITM Testing	Check for resistance to proxying or interception (e.g., Burp Suite, MITMproxy)	Successful or blocked interception logs
13	Patch & Update Mechanism	Review software update mechanism for security (e.g., signature verification)	Update flow test, check for unsigned update executables
14	Debugging & Tampering	Test app behavior when debugged, patched, or modified using tools like OllyDbg	Screenshots of memory patching, app crash or behavior change
15	API Security Testing	Intercept and test backend API calls for auth, validation, and injection flaws	API request logs, Burp Suite results
16	DLL Hijacking / Injection	Attempt to load or replace libraries the app loads dynamically	DLL injection PoC, loaded modules list
17	Clipboard & Interprocess Comm.	Assess clipboard handling and IPC channels for data leakage risks	Clipboard snooping result, named pipe access logs
18	Sandboxing & Privileges	Ensure app runs with least privileges, no admin rights required unnecessarily	App launch context, Windows UAC prompt test
19	Malware or AV Evasion Checks	Check if app behavior resembles malware or evades endpoint protections	Behavior monitoring tool results (Sysmon, EDR logs)
20	Compliance Mapping	Map vulnerabilities to frameworks like OWASP, ISO 27001, NIST	OWASP Desktop Top 10 or NIST SP 800-53 alignment

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🔧 Tools Commonly Used

Purpose	Tools
Static Analysis	Ghidra, IDA Pro, dotPeek, dnSpy
Dynamic Behavior Analysis	ProcMon, Process Hacker, RegShot
Debugging	x64dbg, OllyDbg, WinDbg
Traffic Interception	Wireshark, Burp Suite, MITMproxy
DLL Injection	PEStudio, CFF Explorer, Custom DLL Injectors
API Testing	Postman, Burp Suite, SoapUI
Encryption & Obfuscation Review	Detect-It-Easy, PEiD, ProGuard (Java)

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📁 Deliverables of Thick Client Audit

Document	Description
Audit Report	Detailed findings with severity ratings (CVSS)
Executive Summary	Risk overview, top findings, business impact
Risk Register	Risks with likelihood, impact, and mitigation strategy
PoC Evidence Screenshots	Screenshots or logs demonstrating vulnerabilities
Remediation Guidance	Fixes for code, configuration, or architecture flaws
Compliance Mapping	OWASP, ISO, PCI DSS, or organization-specific framework alignment

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📊 Sample Risk Example

Vulnerability	Impact	Likelihood	Risk Level	Mitigation
Hardcoded credentials	High	High	Critical	Move secrets to secure vault or keychain
Weak encryption algorithm	Medium	High	High	Use AES-256 with proper key management
DLL Hijacking	High	Medium	High	Use signed libraries and load with full path
Plaintext communication	High	High	Critical	Implement TLS 1.2+ and certificate pinning
Local data leakage	Medium	Medium	Moderate	Encrypt sensitive local storage

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Would you like:

• A Thick Client Audit Report Template (Word/Excel)?
• A PoC document for DLL Injection or Reverse Engineering?
• Or a checklist aligned to OWASP Desktop App Top 10?