fix: resolve executables against PATH not cwd on Windows; reject %VAR% paths - #1905
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fix: resolve executables against PATH not cwd on Windows; reject %VAR% paths#1905iankhou wants to merge 3 commits into
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Dependency Review✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.Scanned FilesNone |
…s; reject %VAR% paths Two Windows-specific hardening fixes to the shared subprocess module, plus a test that actually exercises the .cmd path. 1. resolveExecutable(): on Windows a bare program name spawned without a shell is searched for in the cwd *before* PATH, so a file planted in a handed-over cloud assembly (e.g. docker.bat) could shadow the real binary. run()/runSync() now resolve the executable to an absolute PATH hit up front and refuse a name that is not on PATH rather than let the cwd satisfy it. POSIX is unchanged (execvp already searches PATH only); explicit paths are honored verbatim. 2. quoteShellPart() (toolkit-lib): cmd.exe expands %VAR% even inside double quotes and a `cmd /c` line cannot reliably escape a percent, so a discovered path carrying a %...% reference is now refused loudly instead of being silently rewritten. 3. Adds a Windows-only test that runs a real .cmd shim with hostile arguments — the one path where cross-spawn's cmd.exe escaping is exercised (a plain .exe never is). NOTE: items 1 and 3 change Windows spawn behavior and must be validated by the Windows integ tests; the resolveExecutable logic is unit-tested cross-platform via a `platform` parameter.
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Pull request overview
Hardens Windows subprocess execution against executable shadowing and unsafe %VAR% path expansion.
Changes:
- Resolves bare Windows executables through PATH before spawning.
- Rejects shell-bound Windows paths containing
%...%. - Adds Windows subprocess and unit coverage.
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
packages/@aws-cdk/private-tools/lib/subprocess/index.ts |
Adds executable resolution and ENOENT handling. |
packages/@aws-cdk/private-tools/test/subprocess/subprocess.test.ts |
Tests PATH resolution and .cmd escaping. |
packages/@aws-cdk/toolkit-lib/lib/api/cloud-assembly/environment.ts |
Rejects unsafe percent-containing paths. |
packages/@aws-cdk/toolkit-lib/test/api/cloud-assembly/environment.test.ts |
Tests percent-path rejection. |
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| .map((e) => e.trim()) | ||
| .filter(Boolean); | ||
| const lower = command.toLowerCase(); | ||
| return configured.some((e) => lower.endsWith(e.toLowerCase())) ? [''] : configured; |
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| for (const dir of dirs) { | ||
| for (const ext of exts) { | ||
| const candidate = path.join(dir, command + ext); |
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Windows integ test verification run: https://github.com/aws/aws-cdk-cli/actions/runs/33107303906
Follow-up to #1763 / #1849. Two Windows-specific hardening fixes to the shared subprocess module, and a test that exercises the
.cmdpath.Summary
resolveExecutable()— on Windows a bare program name spawned without a shell is searched for in the working directory before PATH, so a file planted in a handed-over cloud assembly (e.g.docker.bat) could shadow the real binary.run()/runSync()now resolve the executable to an absolute PATH hit up front and refuse a name that is not on PATH rather than let the cwd satisfy it. POSIX is unchanged (execvp already searches PATH only); an explicit path (absolute or containing a separator) is honored verbatim.quoteShellPart()(toolkit-lib) — cmd.exe expands%VAR%even inside double quotes, and acmd /ccommand line cannot reliably escape a percent (doubling only works in batch files). A discovered path carrying a%...%reference is now refused loudly instead of being silently rewritten (an env var spliced into the path).A Windows-only test that runs a
.cmdshim with hostile arguments — the one path where cross-spawn's cmd.exe escaping is exercised (a plain.exe, as in every existing test, never is).Testing
resolveExecutable.cmdhostile-args test run on Windows integ workflow.environment.test.tsChecklist
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license.