AI agents use upload_file to create or update resources in Mythic MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mythic MCP environment.
Upload operations create or place files on target systems, making this a Write action. Given the C2 penetration testing context and sibling tools that execute code and commands, file uploads could deliver malicious payloads or modify system state with significant impact, warranting high severity. Confidence is moderate-high because the description is empty, but the tool name and server context are clear.
From the tool's definition Tool named 'upload_file' with no description; context indicates it operates within a Mythic C2 (Command & Control) penetration testing framework alongside tools like execute_mimikatz, run_shell_command, and run_as_user.
Documented attack patterns abuse exactly the kind of access upload_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Mythic MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for upload_file:
{
"version": "1",
"default": "deny",
"tools": {
"upload_file": {
"limits": [
{
"counter": "upload_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}upload_file 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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upload_file. It is categorised as a Write tool in the Mythic MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Mythic MCP server in PolicyLayer and add a rule for upload_file: 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 Mythic MCP. Nothing to install.
upload_file 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 upload_file 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 upload_file. 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.
upload_file is provided by the Mythic MCP server (xpn/mythic_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 6 Mythic MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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6 Mythic MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.