Core.Scripting-012 (High, Security) resolution.
The Core.Scripting-008 rewrite broadened the BCL references list from a
narrow allow-list to the full System.* + netstandard +
Microsoft.Win32.Registry set, delegating the security gate entirely to
ForbiddenTypeAnalyzer. Three categories of dangerous BCL types were
reachable from script source without a deny-list entry:
- System.Threading.ThreadPool — QueueUserWorkItem re-introduces the
background-fanout threat Core.Scripting-003 closed against
System.Threading.Tasks.
- System.Threading.Timer — schedules unbounded callback work that
outlives the per-evaluation timeout.
- System.Runtime.Loader.AssemblyLoadContext — loads arbitrary DLLs.
Defense-in-depth gap; invocation needs reflection (already denied)
but the load itself was reachable.
Fix:
- Added 'System.Runtime.Loader' to ForbiddenNamespacePrefixes
(preferred over type-granular per the recommendation so future BCL
additions to that namespace are denied by default).
- Added 'System.Threading.ThreadPool' and 'System.Threading.Timer'
to ForbiddenFullTypeNames — both live in System.Threading shared
with allowed primitives so they must be type-granular.
Regression tests added to ScriptSandboxTests:
Rejects_ThreadPool_QueueUserWorkItem_at_compile
Rejects_Timer_new_at_compile
Rejects_AssemblyLoadContext_at_compile
Docs:
docs/v2/implementation/phase-7-scripting-and-alarming.md decision #6
and the Sandbox-escape compliance-check row both updated to enumerate
the new entries per the Core.Scripting-009 doc-sync convention.
Two lower-impact suggestions from the finding's recommendation
(System.Console, CultureInfo.DefaultThreadCurrentCulture) were
intentionally not addressed and are recorded as accepted minor risks
in the resolution.
Verification: Core.Scripting.Tests 107/107 (was 104 + 3 new rejection
tests).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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