How do I harden the NSIS stubs in such a way that I don't lose system.dll feature. If ACG not possible, how can I protect against it?

GPT-5.4

Vote: No

I keep vote B. The strongest interpretation of the binary choice is whether you can harden NSIS stubs in a way that preserves system.dll while achieving the kind of protection ACG would provide. The answer remains no. system.dll depends on runtime dynamic call machinery that conflicts with ACG-style restrictions on dynamic executable code. Gemini's argument mainly says "yes, you can still harden with other mitigations." That is true as a practical defense-in-depth point, but it does not establish compatibility with ACG or an equivalent substitute that preserves the same security property. It reframes the question from compatibility to partial mitigation. Claude and Kimi reinforce the key technical point: ACG blocks the executable-memory behavior system.dll relies on. Other controls like CFG, DEP, ASLR, CIG, code signing, reduced privileges, and plugin minimization are worthwhile, but they are compensating controls, not a full solution. So the best final answer is B: you cannot fully do this without losing system.dll functionality; if ACG is not possible, you can only mitigate risk with layered protections.

Claude Opus 4.6

Vote: No

I'm maintaining my vote of B (No). The question asks whether you can harden NSIS stubs without losing system.dll functionality, specifically asking about ACG. The direct answer to 'can ACG work with system.dll' is definitively No. Gemini's argument for A is interesting — they interpret the question as 'is it possible to harden NSIS stubs at all without breaking system.dll?' and answer Yes because alternative mitigations exist. That's a reasonable interpretation, but I think it misreads the question's emphasis. The question specifically asks about ACG first, then asks how to 'protect against it' — meaning protect against the same class of attacks ACG addresses. The honest answer is that you cannot achieve equivalent protection to ACG while keeping system.dll, because system.dll's core mechanism (dynamic code generation) is exactly what ACG prevents. Alternative mitigations like DEP, ASLR, CFG, and CIG are valuable defense-in-depth measures, but they do not provide the same protection as ACG against dynamic code injection attacks. As GPT-5.4 correctly noted, you can reduce risk but not fully preserve the feature while claiming equivalent security guarantees. The binary choice here should reflect the fundamental incompatibility: No, you cannot fully harden NSIS stubs against arbitrary code execution (what ACG protects against) while retaining system.dll's dynamic code generation capabilities. The alternatives are mitigations, not solutions.

Gemini 3.1 Pro (changed mind)

Vote: No

Claude Opus 4.6 makes a highly compelling point: while the prompt is technically phrased as a 'How do I...' question, the core implicit inquiry is whether it is possible to use Arbitrary Code Guard (ACG) while preserving the functionality of system.dll. Because system.dll fundamentally relies on the dynamic generation of executable code (thunks) at runtime to interact with arbitrary Windows APIs, it is intrinsically incompatible with ACG, which strictly blocks the allocation of new executable memory pages. Therefore, the answer to whether you can achieve this specific harmony is definitively 'No'. Since full ACG protection is impossible without breaking the feature, we are left only with defense-in-depth mitigations (like CFG, ASLR, DEP, and code signing). Recognizing the strict impossibility of the ideal scenario, I am changing my vote to B.

Kimi K2.5

Vote: No

The question centers on whether you can harden NSIS stubs against arbitrary code execution while preserving system.dll functionality, specifically referencing ACG. ACG (Arbitrary Code Guard) prevents dynamic code generation, which is the core mechanism system.dll uses to create thunks for arbitrary Windows API calls. This is a fundamental architectural conflict: system.dll requires executable memory allocation and runtime code modification, while ACG explicitly blocks these operations. While alternative mitigations like CFG, CIG, DEP, and ASLR reduce the attack surface (as Gemini correctly notes), they do not prevent the specific vulnerability class that ACG addresses—malicious use of dynamically generated code. Since system.dll itself enables dynamic code execution patterns that bypass static analysis and CFI protections, you cannot achieve ACG-equivalent hardening without removing the feature. The answer is therefore No: you must choose between system.dll's dynamic capabilities and ACG-level protection against arbitrary code execution.

Final Summary

The AI Roundtable initially split over whether 'hardening' meant achieving specific ACG-level security or simply applying general mitigations, with Gemini 3.1 Pro standing alone in the 'Yes' camp. However, a sharp technical critique from Claude Opus 4.6 convinced the group that because system.dll fundamentally relies on dynamic code generation—the very thing ACG is designed to kill—you cannot truly harden the stub while preserving the feature. The debate concluded with a unanimous consensus that technical incompatibility makes a complete solution impossible.

All 4 models agreed on "No" after discussion

Strongest Arguments

• No: System.dll functions by dynamically generating executable 'thunks' at runtime to call Windows APIs, a behavior that is fundamentally and architecturally blocked by Arbitrary Code Guard (ACG).

Key Turning Points

• Claude Opus 4.6 argued that the question isn't just about 'mitigation' but whether ACG-equivalent protection can coexist with system.dll, which it cannot.
• Gemini 3.1 Pro abandoned its 'Yes' vote after acknowledging that alternative mitigations like ASLR and DEP do not provide the same security guarantees as the blocked ACG.