nemu_xor_region
XOR a region of emulated memory with a single-byte key. Returns the XOR result as base64. Use for quick decryption testing — XOR a buffer with a candidate key byte and inspect the preview without modifying guest state. Set dryRun=false to write the XOR result back into guest memory.
This record as markdown: /tools/io-github-vmoranv-jshookmcp/nemu-xor-region.md
What nemu_xor_region does on Jshookmcp
AI agents invoke nemu_xor_region 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_xor_region is rated High
Modifies emulated guest memory state when dryRun=false, executing a memory write operation.
From the tool's definition XOR a region of emulated memory...write the XOR result back into guest memory
Attacks that exploit this kind of access
The rule that runs nemu_xor_region 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_xor_region, this is the rule to start with:
nemu_xor_region 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_xor_region call is checked against it from then on.
Questions about nemu_xor_region
XOR a region of emulated memory with a single-byte key. Returns the XOR result as base64. Use for quick decryption testing — XOR a buffer with a candidate key byte and inspect the preview without modifying guest state. Set dryRun=false to write the XOR result back into guest memory. 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_xor_region: 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_xor_region 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_xor_region 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_xor_region. 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_xor_region 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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