Files
shopdb-flask/agent
Proudlock 702eeb3e52 Fix CRITICAL and HIGH security vulnerabilities in certificate renewal
Addresses all critical and high-severity findings from Fable security review.

CRITICAL FIX #1: Server Certificate Validation Bypass
- File: CertificateRenewal.cs
- Issue: Agent accepted ANY server certificate when ServerCertThumbprint not configured
- Fix: Now validates against Windows trusted roots when pinning not configured
- Impact: Prevents MITM attacks during renewal requests

CRITICAL FIX #2: Certificate Revocation Check Incomplete
- Files: asset.py, client_cert.py, migration 0022
- Issue: Revocation check used hasattr() and silently skipped when columns missing
- Fix: Applied migration 0022, uncommented revocation columns, removed hasattr()
- Impact: Revoked certificates can no longer authenticate or renew

CRITICAL FIX #3: Expired Certificates Cannot Renew
- Files: routes.py (renewal endpoint), CertificateRenewal.cs
- Issue: Expired certs fail at TLS handshake before reaching renewal endpoint
- Fix: Added API key + hostname fallback for renewal when cert expired
- Agent now sends hostname in request body for API key authentication
- Impact: Agents can renew expired certificates, 30-day window becomes effective

HIGH FIX #4: Hostname Injection Vulnerability
- File: routes.py
- Issue: No validation before passing hostname to certificate generation
- Fix: Added regex validation - 1-64 chars, alphanumeric plus dot/hyphen/underscore
- Impact: Prevents injection attacks via malicious hostnames

HIGH FIX #5: Rate Limit Bypass via Clock Manipulation
- File: routes.py
- Issue: Naive UTC datetime arithmetic vulnerable to timezone changes
- Fix: Use timezone-aware datetime with explicit UTC conversion
- Impact: Rate limit cannot be bypassed via clock manipulation

HIGH FIX #6: Hard Process Termination Loses In-Flight Work
- File: Program.cs
- Issue: Environment.Exit(0) aborted in-flight work and could corrupt state
- Fix: Graceful return from RunHostAsync() instead of Environment.Exit()
- Impact: Service exits cleanly, no lost telemetry or corrupted local state

HIGH FIX #7: Missing Database Transaction Isolation
- File: routes.py
- Issue: Race condition in concurrent renewal requests
- Fix: Added with_for_update() row-level locking for both auth paths
- Impact: Prevents concurrent renewals from bypassing rate limit

MEDIUM FIX #8: Missing Audit Logging for Failures
- File: routes.py
- Issue: Failed renewal attempts not captured in audit trail
- Fix: Added AuditLog.log() for cert generation and database update failures
- Impact: Security monitoring can detect repeated renewal failures

SECURITY HARDENING:
- Server cert validation: Never accepts certificates blindly
- Revocation enforcement: Fail closed if columns missing
- Expired cert handling: Dual-auth allows renewal while maintaining security
- Input validation: Hostname must match safe character set
- Transaction safety: Row locks prevent race conditions
- Audit trail: All failures logged for security monitoring

OPERATIONAL IMPROVEMENTS:
- Agents can now renew expired certificates (no more manual intervention)
- Graceful shutdown prevents data loss during renewal
- Rate limiting immune to timezone issues
- Comprehensive audit trail for troubleshooting

ADR COMPLIANCE:
- Maintains ADR-001 (Asset as platform contract)
- Maintains ADR-006 (Collector contract - backward compatible)
- Database naming (snake_case columns)
- No unicode/emojis
- Security best practices: ALL CRITICAL/HIGH issues resolved

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-09-14 14:18:35 -04:00
..

ShopDB Endpoint Agent

A Windows telemetry agent that reports endpoint state to a ShopDB server's endpoints plugin. It runs as a Windows service in production and as a console app for development and testing.

Projects

  • ShopDbEndpointAgent.Core - contracts, config, logging, collection, and the resilient collector HTTP client. No host concerns; unit-testable.
  • ShopDbEndpointAgent - the service host (generic host + Windows service lifetime). Composes Core through DI. This is the telemetry runtime.
  • ShopDbEndpointAgent.Tray - interactive user-session tray app: a system-tray icon with "Send Status now" (on-demand report) and the 5-click issue reporter (ServiceNow flow is still a scaffold). Separate process from the service, because a SYSTEM service cannot draw a tray icon in a user session.

Configuration

Runtime config is layered. Non-secret defaults live in appsettings.json (shipped with the build). The collector key and base URL are provisioned out of band in the registry and win over appsettings.json, so a distributed build never carries the secret and the site can rotate the key without a rebuild.

Registry (production)

Create these values under HKLM\SOFTWARE\GE\ShopDB (64-bit view):

Value Type Meaning
BaseUrl String https://shopdb.example.net (server root)
CollectorKey String The endpoint agent key from Settings -> Endpoints -> Key management

Example (elevated PowerShell):

New-Item -Path 'HKLM:\SOFTWARE\GE\ShopDB' -Force | Out-Null
Set-ItemProperty -Path 'HKLM:\SOFTWARE\GE\ShopDB' -Name 'BaseUrl' -Value 'https://shopdb.example.net'
Set-ItemProperty -Path 'HKLM:\SOFTWARE\GE\ShopDB' -Name 'CollectorKey' -Value '<paste the generated key>'

appsettings.json (all environments)

Key Default Meaning
baseurl "" Dev fallback for the server root (registry wins).
apikey placeholder Dev fallback for the collector key (registry wins).
cadenceseconds 900 Report interval (15 min).
jitterseconds 60 Random +/- spread on the interval (anti-herd).
adoptonfirstrun true Send adopt=true on first contact only.
utilitiespath "" Directory of site PowerShell "agent utilities".
logpath "" Override the rolling log directory.

For a dev box, set baseurl and apikey here and skip the registry.

Running

Console (dev), one report then exit:

dotnet run --project ShopDbEndpointAgent -- --once

Console (dev), continuous cadence loop:

dotnet run --project ShopDbEndpointAgent -- --console

Install as a Windows service

Publish self-contained, then register with sc.exe (elevated):

dotnet publish ShopDbEndpointAgent -c Release -r win-x64 --self-contained -o C:\ProgramData\ShopDB\EndpointAgent\bin
sc.exe create "ShopDBEndpointAgent" binPath= "C:\ProgramData\ShopDB\EndpointAgent\bin\shopdb-endpoint-agent.exe" start= auto DisplayName= "ShopDB Endpoint Agent"
sc.exe description "ShopDBEndpointAgent" "Reports endpoint telemetry to ShopDB."
sc.exe start "ShopDBEndpointAgent"

The service runs as LocalSystem by default, which it needs to read the Security event channel and system WMI.

Tray app (system-tray icon)

The tray is a per-user process, not a service, so it starts at sign-in rather than under sc.exe. The generated install.ps1 handles it: it copies shopdb-endpoint-tray.exe next to the agent and registers a machine-wide logon autostart (HKLM\Software\Microsoft\Windows\CurrentVersion\Run\ShopDbEndpointTray, 64-bit view). The installer deliberately does NOT start the tray itself: it runs elevated, so any process it starts inherits an admin token, and mapped drives are per logon token - an elevated tray probes the wrong drive table. The Run key only fires at logon, which would leave the tray dead until sign-out on a machine someone is already using, so the installer also registers a transient ShopDB tray first launch scheduled task under S-1-5-32-545 at RunLevel Limited, runs it once, and unregisters it. That task is the only mechanism that can reach into an existing interactive session without carrying the installer's token. Pass -NoTray for a headless, service-only install.

User-context collection does not depend on the tray. The installer registers a ShopDB user-context probe scheduled task against the Users group at RunLevel Limited, which runs shopdbagent.exe --collect-usercontext in the operator's own session at logon and every 30 minutes.

Right-click the tray icon for:

  • Send Status now - reports this PC to ShopDB immediately so the monitor page refreshes without waiting for the next cadence tick. It shells out to shopdbagent.exe --once, reusing the exact production collection path; the tray holds no collector key. A balloon tip reflects success or failure (on failure, see the rolling agent log).
  • Report an issue... - the ServiceNow ticket flow (scaffold; submission path is an open decision).

A desktop shortcut to shopdb-endpoint-tray.exe can be added later for an explicitly launchable ServiceNow surface.

WebUI command execution model (security context)

The WebUI can send an endpoint an allowlisted command (server source of truth: plugins/endpoints/commands.py; agent handler: CommandExecutor). The agent service runs as LocalSystem, but not every command runs in that context. The launch context is chosen per action so processes surface to the operator while privileged operations keep the token they need:

  • Generic process_start (for example DncMain, UDC) launches into the ACTIVE CONSOLE USER's session at medium integrity, so the app is visible on the operator's desktop. CyberArk/EPM brokers any elevation afterward.
  • Generic process_stop / process_status run as SYSTEM (kill and probe).
  • service_start / service_stop / service_status run as SYSTEM, because service control requires the admin/SYSTEM token.
  • mtconnect_start / mtconnect_stop / mtconnect_status all run as SYSTEM, because MTConnect is the "UDC MTConnect Agent" Windows service and service control requires the admin/SYSTEM token. mtconnect_start runs install.bat (Agent.exe install) to install or repair the service, then ensures it is running; mtconnect_stop stops the service; mtconnect_status queries it. run.bat (agent.exe run agent.cfg) is a foreground TESTING launcher and is deliberately NOT used by the agent.
  • system_restart runs as SYSTEM and reboots the machine immediately via shutdown.exe /r /t 0 (no grace timer). It is a fixed action with no target, gated server-side by the dedicated endpoints.restart permission on top of endpoints.command, and fronted by a WebUI confirmation gate.

Do not route MTConnect through the generic process_start user-session path or service control breaks. MTConnect is intentionally absent from the process_start launch map for the same reason; the fixed mtconnect_* handler owns it.

Behavior note for redeploys: the MTConnect service-control model is a runtime change, so the agent must be rebuilt and redeployed for it to take effect. Server-side command/allowlist/RBAC changes are picked up by the container rebuild; rebuild and redeploy the agent whenever the runtime launch/control logic itself changes.

Diagnostics

  • Rolling file log: %ProgramData%\ShopDB\EndpointAgent\logs\YYYYMMDD-agent.log (14-day retention).
  • Windows Event Log: agent runtime failures and unhandled exceptions are written to the Application log under source ShopDB Endpoint Agent. The source is created on first elevated run (or by the installer). Filter Event Viewer by that source to see agent/system interop failures.

Agent utilities (PowerShell seam)

If utilitiespath points at a directory, the runtime runs each *.ps1 there per report, parses its JSON stdout, and merges the result into the report. This is the seam the future server-side "Agent configuration" settings page uses to push site-authored collectors down. Scripts must be code-signed and allow-listed before this is enabled in the field (rollout concern).

Logging extensibility

All runtime code logs through Microsoft.Extensions.Logging (ILogger). Adding a sink later (a ShopDB HTTP sink, Seq, syslog) is a host-builder change in Program.cs::ConfigureLogging with no changes to the worker, collector, or client.