nemu_call_symbol
Invoke an exported function by name following AArch64 AAPCS (integer args in x0..x7, result in x0). Auto-detects JNI signatures. Set injectJni=false to force raw arguments. Set debug=true for auto-NOP on NULL indirect calls + auto TLS prep.
This record as markdown: /tools/io-github-vmoranv-jshookmcp/nemu-call-symbol.md
What nemu_call_symbol does on Jshookmcp
AI agents invoke nemu_call_symbol to trigger actions in Jshookmcp. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why nemu_call_symbol is rated High
Arbitrary function invocation on a system can execute code with unpredictable effects and side effects.
From the tool's definition Invoke an exported function by name, AArch64 AAPCS, auto-detects JNI signatures
Attacks that exploit this kind of access
The rule that runs nemu_call_symbol safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For nemu_call_symbol, this is the rule to start with:
nemu_call_symbol stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every nemu_call_symbol call is checked against it from then on.
Questions about nemu_call_symbol
Invoke an exported function by name following AArch64 AAPCS (integer args in x0..x7, result in x0). Auto-detects JNI signatures. Set injectJni=false to force raw arguments. Set debug=true for auto-NOP on NULL indirect calls + auto TLS prep. It is categorised as a Execute tool in the Jshookmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Jshook MCP server in PolicyLayer and add a rule for nemu_call_symbol: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Jshookmcp. Nothing to install.
nemu_call_symbol is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the nemu_call_symbol rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for nemu_call_symbol. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
nemu_call_symbol is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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