nemu_mem_shadow
Add a shadow memory overlay at a specific address. Reads from shadow take priority over underlying memory — use to provide mock data at addresses that would otherwise crash (e.g. address 0 where SO ELF header resides). Does NOT modify the underlying SO mapping.
This record as markdown: /tools/io-github-vmoranv-jshookmcp/nemu-mem-shadow.md
What nemu_mem_shadow does on Jshookmcp
AI agents use nemu_mem_shadow to create or update resources in Jshookmcp, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Jshookmcp environment.
Why nemu_mem_shadow is rated Medium
Creates a virtual memory overlay; modifies emulator state but not underlying data.
From the tool's definition Add a shadow memory overlay at a specific address
Attacks that exploit this kind of access
The rule that runs nemu_mem_shadow 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_mem_shadow, this is the rule to start with:
nemu_mem_shadow stays usable, but capped: an agent stuck in a loop can't make hundreds of changes 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_mem_shadow call is checked against it from then on.
Questions about nemu_mem_shadow
Add a shadow memory overlay at a specific address. Reads from shadow take priority over underlying memory — use to provide mock data at addresses that would otherwise crash (e.g. address 0 where SO ELF header resides). Does NOT modify the underlying SO mapping. It is categorised as a Write tool in the Jshookmcp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Jshook MCP server in PolicyLayer and add a rule for nemu_mem_shadow: 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_mem_shadow is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the nemu_mem_shadow 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_mem_shadow. 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_mem_shadow 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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