Download a file from a URL into the samples directory for analysis.
AI agents use download_from_url to create or update resources in REMnux MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your REMnux MCP Server environment.
This tool fetches external content and writes it to the local filesystem (samples directory). While it is a network fetch (Read-like), the primary effect is creating a new file on disk, making it Write. However, in a malware analysis context, downloading arbitrary files from URLs carries high risk — an AI agent could download malicious payloads onto the analysis system.
From the tool's definition Download a file from a URL into the samples directory for analysis
Documented attack patterns abuse exactly the kind of access download_from_url gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and REMnux MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for download_from_url:
{
"version": "1",
"default": "deny",
"tools": {
"download_from_url": {
"limits": [
{
"counter": "download_from_url_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}download_from_url 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.
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Download a file from a URL into the samples directory for analysis. It is categorised as a Write tool in the REMnux MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the REMnux MCP Server MCP server in PolicyLayer and add a rule for download_from_url: 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 REMnux MCP Server. Nothing to install.
download_from_url 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 download_from_url 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 download_from_url. 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.
download_from_url is provided by the REMnux MCP Server MCP server (remnux/remnux-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 14 REMnux MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
14 REMnux MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.