MSI 1.3 (D-377) installed the loader under Program Files, where nothing removed it: a
customer found the file on every device. Everything of ours lives under ProgramData.
- Package.wxs 1.4.0: the loader copy goes back to <base>\Msi (new component GUID); the
deferred SYSTEM action, started in System32, reads the copy once, checks our signature
and the publisher pin on those bytes and runs those bytes from memory, so a file a user
planted at that path leads to nothing and no handle keeps the installer from removing
the copy. Every bracket and brace is escaped for the Windows Installer formatter.
- Install-AutopilotMonitor.ps1 2.9: Remove-MsiTransportFolder removes the copy in the
agent-present branch (install and skip clear the base already) and an agent folder that
is then empty; Remove-LegacyMsiLoaderFolder removes MSI 1.3's folder under Program Files
in every outcome while devices still enroll with 1.3.
- Tests: installer unit tests for both functions; the loader's MSI contract; the harness
asserts after every run that nothing exists outside ProgramData, runs the MSI 1.4 action
read from Package.wxs (valid, foreign, unsigned, changed; install, skip, marker only,
agent present) and expects MSI 1.3's folder gone; BootstrapContractTests pin the
directory chain, the publisher pin, the escapes and the working directory.
- build-msi.yml: smoke job installs the built MSI on windows-2022/2025 with the deployment
marker set and expects nothing under ProgramData or Program Files, then uninstalls.
- internal: D-384, footprint doc, plan, lessons, backlog.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Findings of a Claude security scan against b4af8c7, each measured first, plus
the MSI channel incident a parallel session found.
- Installer 2.8 extracts the agent ZIP with its own containment check
(Expand-AgentPayload): every entry is resolved against the payload folder
before the first write, a rooted or escaping name refuses the package. The
inbox Expand-Archive of Windows PowerShell 5.1 already refuses such entries
(measured), so the finding was not exploitable as reported; the guarantee is
now the script's own, pinned by tests, and Expand-Archive is banned.
- Installer 2.8 also moves PowerShell's own location out of the agent folder
(Set-Location): on the MSI channel the location pointed at the deleted Msi
folder and the agent start failed with error 267 since 2.7 went live. When
the agent program never started, the Agent folder is removed again so a later
run can install; the stderr line is flattened to one line.
- Run folders younger than an hour stay (a loader may still run there); the
loader's log is taken only from a run folder that is ours.
- Loader 1.4 (minimum installer 2.8) checks before every download attempt that
its run folder is still a real folder of ours, opens the download for reading
before the signature and identity checks and holds it until the run ends, so
what it checked is what runs and nothing can replace or delete it meanwhile.
- Agent: the protected folder security names Administrators as owner; a folder
with another owner or a reparse point is not taken as protected, reparse points
are refused, the base is created protected, install mode protects base and
Agent and refuses to install when it cannot; every start re-checks both.
- Bootstrap MSI 1.3.0 installs its loader under Program Files, where a standard
user cannot create the folder first.
- Tests: containment table, hour rule, held handle, owner and junction tests
(ElevatedFact for the owner assignment), MSI location contract; harness
scenarios for an escaping package (installer and OOBE script), the hour rule,
the Program Files layout and an agent that does not start, with the install
stand-in starting a real program from PowerShell's location. OOBE golden
regenerated.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
GitHub Actions runs powershell steps with $ErrorActionPreference = 'stop', and
under Windows PowerShell 5.1 a stderr line of a native process redirected with
2>&1 then ends the test: the three publish refusals failed in CI although the
publish refused as it should. The publish dry runs now start pwsh through
System.Diagnostics.Process like every other scenario. Local run under 'stop':
199 of 199.
[skip actions]: published by a dispatch of publish-scripts.yml, channel dev first.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- Loader 1.3 downloads into a protected run folder of its own
(%ProgramData%\AutopilotMonitor-Loader-<8 hex>), runs the installer only when it
is signed by the pinned publisher and declares the installer role and version
2.7 or later, removes the folder after a successful run and never touches the
agent folder. Unbound arguments now reach the installer by name; the array
splat bound them by position.
- Installer 2.7 refuses without elevation and decides before it writes: guards
read HKLM through the 64-bit view (a 32-bit host never saw the deployment
marker), guard 5 is covered by the agent check. An agent's folder stays as it
is, a skip without agent removes the folder, an install starts from an emptied,
protected folder and stages the ZIP in a run folder. It moves the MSI's working
directory out, writes stderr only on failure and removes the copy older loaders
left at the fixed path.
- Help texts of both scripts state what customers need; .CHANGELOG, which made
Get-Help ignore the help, gives way to the Platform Changelog.
- OOBE go-script: the installer's shared helpers, its own elevation check
(#Requires is ignored under irm | iex), a run folder.
- Publish: version read line-anchored, the loader's own check on the exact
publish bytes, installers before loaders, -Channel dev (dispatch input).
- Bootstrap MSI 1.2.0; Test-ShouldBootstrapAgent reads the 64-bit view;
Uninstall removes loader run folders and keeps the Deployed marker.
- Tests: Pester unit suites, an integration harness running the real scripts
(loader 1.2 and the MSI 1.0 runner frozen in TestData), BootstrapContractTests;
the gate runs on windows-2022 and windows-2025, once more as SYSTEM, and against
a real standard user.
[skip actions]: published by a dispatch of publish-scripts.yml, channel dev first.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Oliver Kieselbach